In this work, an injection-lockable push-push oscillator operating at 421 GHz is presented. The circuit is based on a 0.5 um transferred substrate InP DHBT MMIC process. A peak output power of -2.4 dBm is measured at 34.6 mW DC-power consumption, resulting in 1.7% DC-to-RF conversion efficiency. The oscillator can be injection-locked through a dedicated locking port which, along with the compact core measuring 0.53 × 0.49 mm2, makes this design suitable for efficient injection-locked oscillator arrays comprising a beam steering function by phase tuning. © 2022 IEEE.

As the maximum frequency of electronics is rising, on-wafer measurements play an important role in modeling of integrated devices. Most of the time, due to the lack of measurement accuracy beyond 110 GHz, such models are usually extracted at frequencies much below their working frequencies and are subsequently extrapolated. The validity of such models is then mostly verified after fabrication of the complete chip, with a simple pass and fail test. This is stating the necessity of enhancing measurement results by any means possible, i.e., to reduce the overall uncertainty in such measurements. It is widely accepted that one of the main sources of uncertainty in such measurements is probe contact repeatability, since it is difficult to reach position accuracy below a few micrometers. We are presenting in this article a method to model the S -parameter variation with probe position on the pads, which can then be used to either estimate contact repeatability uncertainty or further enhance measurement results. The approach is validated based on the measurements performed at 500 GHz. © 1963-2012 IEEE.

Well-defined hetero-interfaces with controlled properties are crucial for any high-performance, semiconductor-based, (opto-)electronic device. They are particularly important for device structures on the nanoscale with increased interfacial areas. Utilizing a ultrahigh-vacuum based multi-tip scanning tunneling microscope, this work reveals inadvertent conductivity channels between the nanowire (NW) base and the substrate, when measuring individual vertical core-shell III-V-semiconductor NWs. For that, four-terminal probing is applied on freestanding, epitaxially grown coaxial p-GaAs/i-GaInP/n-GaInP NWs without the need of nanoscale lithography or deposition of electrical contacts. This advanced analysis, carried out after composition-selective wet chemical etching, reveals a substantially degraded electrical performance of the freestanding NWs compared to detached ones. In an electron beam induced current mode of the nanosensor, charge separation at the substrate-to-NW base junction is demonstrated. An energy dispersive X-ray spectroscopic linescan shows an unintended compositional change of the epitaxially grown NW toward the planar layers caused by different incorporation mechanisms of Ga and In at the NW base. This approach provides direct insight into the NW-substrate transition area and leads to a model of the conductivity channels at the NW base, which should, in principle, be considered in the fabrication of all NW heterostructures grown bottom-up on heterogeneous substrate materials. © 2022 The Authors. Advanced Materials Interfaces published by Wiley-VCH GmbH.

We report on the design, fabrication, and characterization of a monolithically integrated epitaxial thin-film resistor for THz applications. The device is made of an n+-InGaAs layer grown lattice-matched on an insulating InP:Fe substrate. In this study, on-wafer vector scattering parameter characterization up to 500 GHz is carried out, the calibration is performed by means of the multiline TRL method. The InGaAs thin-film resistor shows very flat frequency response in the range from 100 GHz to 500 GHz. An experiment designed to investigate the resistor's temperature dependence and stability up to 120 °C has also been carried out. © 2022 IEEE.

This work focuses on causes and improvements of non-linear behavior of InP DHBTs from a physical simulation point of view. The simulated devices are based on triple mesa structures with type-I band alignment employing a carbon doped In53.2Ga46.8As base, 0.5 μm emitter width and InGaAsP material in the collector region to improve the electron transport. Simulated OIP3 values differed by about 5 dB between two devices. RF performance, in terms of transit frequency and maximum frequency of oscillation, differed by about 75 GHz and 87 GHz for the same device designs. The improved design also showed better electron transport across the collector region, underlining the high sensitivity of device performance effected by the collector design. © 2022 IEEE.

THz oscillators with on-chip antennas containing no ground plane are affected by substrate modes and therefore undirected radiation into free space. When integrating such antennas with focusing lenses, accurate sub-μm alignment is required. This work presents an assembly process utilizing an HRFZ-Si transfer substrate between the InP RTD chip and a hyper-hemispherical silicon lens, enabling precise alignment. We developed a bonding process for 1.2 × 1.2 mm2 InP RTD chips with an optical adhesive utilizing an advanced sub-micron bonder. THz-TDS measurements of the HRFZ silicon wafer were carried out to analyze the losses within the created setup by EM simulations. The assembly process was verified with measurements of a 300 GHz triple barrier (TB)-RTD oscillator using an SBD detector. © 2022 IEEE.

A broadband THz detector consisting of a triple-barrier InP Resonant Tunneling Diode (RTD) with a monolithically integrated circularly polarized spiral antenna is designed, fabricated, and measured at room temperature. A free space measurement setup is utilized for far-field characterization. The detector (evaluated at zero-bias) is illuminated by a chopped continuous wave signal in the 220-330 GHz band, and the direct detection scheme consists of a lock-in amplifier in voltage mode readout. The measured average responsivity RV is in the range of 750 V/W with a peak of 900 V/W at 257.5 GHz, with the lowest calculated NEP of 2.5 pW/√Hz. © 2021 IEEE.

This paper presents an on-chip 1 to 4 subarray element for wireless subharmonic injection (WSI) in the context of antenna-in-antenna THz oscillators. The proposed antenna receives the third-order subharmonic injection signal (SIS) at 100 GHz from one side and radiates the 300 GHz fundamental oscillation signal (FOS) to the opposite side, which performs like a subharmonic transmitarray. Each element is consisted of a single SIS receiving antenna (Receiver antenna, RA) connected with a 2×2 FOS array (Transmitter antenna, TA). By positioning more FOS antenna around the single SIS antenna, the element spacing at 300 GHz is shorted within one wavelength which inhibits the grating lobe. Through tuning the distance of the FOS array element, the surface wave in the thick indium phosphide (InP) substrate is also reduced to some degree. The simulation results show that the maximum radiation efficiency of the designed chip antenna structure is better than 50% in both the 100 GHz and the 300 GHz band. The conjugate impedance matching in the dual-band is achieved according to the active element requirement. Utilizing the antenna proposed in this work, a low injection loss is verified in the periodical boundary based WSI simulation. © 2021 IEEE.

In this paper, we present a comprehensive study of position-defined Al-polar AlN nucleation on lithographically patterned Si(1 1 1) substrates as a method to obtain ordered Ga-polar GaN nanowire arrays, with possible application in future nanowire-based devices such as LEDs and photoelectrochemical water-splitting cells. In a hydrogen processing step, ex situ prepared oxide on pre-structured Si-pillars could be selectively removed. This enabled Al-polar AlN nucleation on the Si-pillar's sidewalls during the following metal–organic vapor phase epitaxy, while dominant N-polar AlN layer growth was observed on the still oxidized Si(1 1 1) horizontal substrate surface neighboring the pillars. 100% of the Ga-polar GaN wires are emerging on the Al-polar AlN growth sites, thus selective area epitaxy without any mask material could be realized. To gain a precise understanding of the growth mechanisms, the attainable Ga-adatom collection area per NW was varied by changing the Si-pillars’ placement pattern. The wire length and diameter increase with extended pitch. At a constant pitch, the size of the wires is adjustable by variation of the Si-pillars’ diameter, therefore growth of GaN wires of controllable dimension and pitch could be attained. Additionally, parasitic NW growth was completely suppressed for any pitch < 3.5 µm, while an increased pitch resulted in additional parasitic growth. Based on these results a model was derived, which includes the site-controlled removal of the oxide, the thus achieved local polarity control of AlN growth, and the influence of the collection area of each NW with respect to their size, whereas the collection area could be set in the experiment by adjustment of the lithographically controlled pitch and growth-parameter dependent Ga-adatom diffusion length. The mask-less polarity- and site-controlled growth of NWs with a height of 5.3 µm ± 0,33 µm and a diameter of 800 nm ± 160 nm at a pitch of 2.5 µm could be attained. Hence, a deep understanding of the growth mechanisms and the geometrical control of polarity- and site-controlled GaN NWs could be achieved, forming the base for development of NW-based devices on a conductive AlN/Si-template. © 2021

The traditional transmission coefficient present in the original Landauer formulation, which is valid for quasi-static scenarios with working frequencies below the inverse of the electron transit time, is substituted by a novel time-dependent displacement current coefficient valid for frequencies above this limit. Our model captures in a simple way the displacement current component of the total current, which at frequencies larger than the inverse of the electron transit time can be more relevant than the particle component. The proposed model is applied to compute the response of a resonant tunneling diode from 10 GHz up to 5 THz. We show that tunneling electron devices are intrinsically nonlinear at such high frequencies, even under small-signal conditions, due to memory effects related to the displacement current. We show that these intrinsic nonlinearities (anharmonicities) represent an advantage, rather than a drawback, as they open the path for tunneling devices in many THz applications, and avoid further device downscaling. © 1980-2012 IEEE.

On-chip antennas with radiation towards the substrate are affected by modest coupling performance to a free-space path. (Hyper-)hemispherical silicon lenses can improve the efficiency of quasi-optical emission and detection even at THz frequencies. This approach requires an alignment accuracy in the $\mu\mathrm{m}$-scale at THz frequencies. In this contribution, we report on the benefit of hyper-hemispherical silicon lenses in terms of relaxed alignment accuracy needs. We present the impact of alignment on quasi-optical measurements using indium phosphide resonant-tunneling diodes. The main components of the resulting setups are discussed while the effect of alignment is quantitatively evaluated for both, hemispherical and hyper-hemispherical silicon lenses. Moreover, design rules and concepts for a heterointegrated system are derived on consecutive observations. © 2021 IEEE.

Herein, a detailed analysis of leakage mechanisms in epitaxially grown nanowire heterojunction bipolar transistors (NW-HBTs) is presented. Coaxial npn-GaAs/InGaP core–multishell nanowires are grown via gold-catalyzed metalorganic vapor phase epitaxy, processed to three terminal devices and electrically characterized. The key for successful NW-HBT device functionality is the identification of tunneling as the dominant leakage mechanism in highly doped nanowire pn-junctions. The suppression of forward tunneling currents by adjustment of the tunneling barrier width reduces the junction leakage current density into the nA cm−2 regime, which is further verified by tunneling-related electroluminescence measurements. In addition, the suppressed tunneling accordingly increases the number of electrons that are injected from the n-emitter into the p-base. The latter effect influences the performance of pn-junction based devices and is found to enable bipolar transistor functionality. Measured common emitter Gummel plots of the NW-HBT exhibit a current gain of up to 9 and the transistor function is additionally verified by current-controlled output characteristics. © 2020 The Authors. Published by Wiley-VCH GmbH

This article presents the design and prototyping of components for a modular multiple-input-multiple-output (MIMO) millimeter-wave radar for space applications. A single radar panel consists of 8 transmitters (TX) and 8 receivers (RX), which can be placed several times on the satellite to realize application-specific radar apertures and hence different cross-range resolutions. The radar chirp signals are generated by SiGe:C BiCMOS direct-digital-synthesizers (DDS) in the frequency range of 1 to 10.5GHz with a chirp repetition rate of &lt; 1μs within each TX and RX. The latter allows for easy interfaces in the MHz range in between the TX/RX units and therefore optimized 2-D sparse antenna arrays with rather large distances in between the TX/RX antennas. Furthermore, this allows for ideally linear frequency modulated continuous-waveforms (FMCW) in conjunction with phase-shift-keying (PSK) radar signals and enables simultaneous operation of all TX when code division multiplex (CDMA) modulation schemes are applied. Comparably low complexity of the TX/RX units has been achieved by applying straightforward frequency plans to signal generation and detection but comes with challenging requirements for the individual active and passive components. Tackled by thin film technology on alumina and the recently developed SiGe and InP semiconductor technologies, which have been further optimized in terms of process maturity and space qualification. Upconversion and downconversion to and from 85 to 94.5GHz are performed by double balanced Gilbert mixers realized with InP double heterojunction bipolar transistor technology (DHBT) and 42-GHz local oscillator signals from SiGe:C BiCMOS VCO synthesizer using phase-locked-loops (PLL). InP DHBT power amplifiers and low-noise amplifiers allow for output power levels of 15dBm and &gt; 30dB gain with noise figure values of 9dB, respectively. The MIMO radar utilizes patch antenna arrays on organic multilayer printed circuit boards (PCB) with 18dBi gain and 18∘ half power beamwidth (HPBW). Generation of power supply and control signals, analog-to-digital conversion (ADC), and radar signal processing are provided centrally to each panel. The radar supports detection and tracking of satellites in distances up to 1000m and image generation up to 20m, which is required to support orbital maneuvers like satellite rendezvous and docking for non-cooperative satellites. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

Metal organic vapor-phase epitaxy of GaN shells on N- and Ga-polar nanowires on AlN/Si(111) templates has been studied in detail. A polarity-dependent epitaxial optimization of nitride-based core-shell structures is necessary to attain the desired shell shape. On N-polar wires, a maximal shell length has been achieved using N2, only, as a carrier gas, while the length decreases by substitution of N2 with H2. A strong impact of the NW growth template polarity has been observed, which has to be considered to attain the desired shell shape. On Ga-polar wires under pure N2, an exclusive coverage of the wire tip occurs. Shell growth and an increasing shell length are obtained by injecting increased H2 flows. The semi-polar {1011} and polar (0001) planes have been identified as the facets that limit the vertical shell length growth evolution on the N- and Ga-polar core-shell structures, respectively. Meanwhile, the m-planar lateral growth mode is found to be identical for both types of polarities. The data are used to set up a growth model that includes the facet-dependent termination, carrier-gas dependent H-passivation, Ga-adatom length and Ga-adlayer formation, and the thereby adjusted three-dimensional growth and shell shape for both polarities. The attained insights and the developed technology allow the epitaxy of homogeneous complex crystal architectures, mandatory for optimized nitride core-shell NW-based devices. This journal is © The Royal Society of Chemistry.

A design for a 300 GHz reflection type push-push oscillator including an input for an external injection locking signal is proposed. The oscillator is based on substrate transferred InP double heterojunction bipolar transistors. The intrinsic performance of the circuit is evaluated in Harmonic-Balance (HB) simulations. Furthermore, the circuit behavior under the influence of an injected signal is investigated in transient simulations and the key parameters for the locking range are derived. Additionally, a comparison of one-sided and differential injection of the locking signal is made and it is shown that the one-sided injection of the locking signal is a viable approach for the here proposed oscillator. © 2020 IEEE.

InP-based electronic technologies are well suited for THz applications due to the combination of high electron velocity and breakdown field in this material system. Today's highest frequency circuits are built from InP HEMT devices, exceeding 1 THz application frequency. The InP heterojunction bipolar transistor (InP HBT) has high potential for further development in the THz frequency range through scaling and process development. A lack of circuit complexity in InP electronic circuit technology compared to CMOS can be mitigated by heterointegration. The concept of vertical integration is of particularly high interest for THz phased arrays. © 2020 IEEE.

A large-signal equivalent circuit model is developed for ultra-high frequency signal generation and detection provided by an InP triple barrier resonant tunneling diode. On-wafer DC and S-parameter measurements on 0.5 um2 and 1 um2 area devices were made from 20 MHz to 67 GHz. The bias dependent measurement data are utilized to extract the parameters of a compact RF model which accurately describes the static and dynamic behavior of the triple barrier resonant tunneling under zero bias and forward bias condition. © 2020 IEEE.

Herein, the characterization of n-doped InGaP:Si shells in coaxial not-intentionally doped (nid)-GaAs/n-InGaP as well as n–p–n core–multishell nanowires grown by metalorganic vapor-phase epitaxy is reported. The multi-tip scanning tunneling microscopy technique is used for contact-independent resistance profiling along the tapered nid-GaAs/n-InGaP core–shell nanowires to estimate the established emitter shell doping concentration to ND ≈ 3 · 1018 cm−3. Contacts on these shells are demonstrated and exhibit ohmic current–voltage characteristics after annealing. Application potential is demonstrated by the growth and processing of coaxial p-GaAs/n-InGaP junctions in n–p–n core–multishell nanowires, with n-InGaP being the electron-supplying emitter material. Current–voltage characteristics and temperature-dependent electroluminescence measurements substantiate successful doping of the n-InGaP shell. A tunneling-assisted contribution to the leakage currents of the investigated p–n junctions is verified by the sub-bandgap luminescence at low temperatures and is attributed to radiative tunneling processes. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

We present Au catalyzed p-GaAs nanowire growth on n-GaN layers as a possible method to grow an arsenide on a nitride compound semiconductor by metal organic vapor phase epitaxy. The GaAs growth position, the nanowire density and the nanowire growth direction are controlled by a combination of vapor-liquid-solid growth and selective area epitaxy. Thus, a spatially controlled nanowire growth is attained, which is mandatory for device fabrication. The growth position is defined by lithographically positioned Au discs on n-GaN. By adapting the growth conditions (QTBAs, presaturation) the nanowire density is optimized. Lateral and vertical anisotropic nanowire growth is attained through VLS growth in structured SiOx openings. Critical technological parameters for successful control of the growth direction are the positioning of the Au catalyst in relation to the SiOx mask, the size of the eutectic in relation to the opening dimensions, and the SiOx thickness. These results lead to distinct pn-junction positions and adjustable nanowire growth dimensions and directions. This journal is © The Royal Society of Chemistry.

Phase and frequency control of resonant tunneling diode (RTD) based terahertz oscillators are major challenges in realizing coherent signal sources for arrayed applications, such as spatial power combining, beam steering, or multi-in multi-out systems. In this letter, we demonstrate frequency locking and control of an RTD oscillating at f0 ∼ 550 GHz, via radiative injection of a weak sinusoidal subharmonic signal at f0/2. Precise frequency control, within the locking range of around 2 GHz, is demonstrated. A peak output power enhancement of 14 dB in the whole locking range, compared to the free running oscillator, is achieved. Furthermore, occurrence of phase locking is identified by the spectral linewidth reduction, quantifiable in the full-width at half-maximum parameter. A signal linewidth of 490 Hz was achieved in locked operation. © 2011-2012 IEEE.

Modeling of quantum devices is still based on the original idea of Landauer that the macroscopic (DC) conductance of electron devices can be related to the (microscopic) transmission coefficient of electrons. In this paper we propose a simple model that captures the role of the particle and displacement currents in quantum electron devices working at THz by substituting the traditional transmission coefficient by a new displacement current coefficient. In particular, our model is used to compute the total current of a Resonant Tunnelling Diode (RTD) device under AC conditions. The new model, based on a time-dependent approach, is firstly shown to reproduce the DC behaviour of the Landauer model. Later on, at input frequencies higher than 500 GHz, large differences between the two models are observed. In particular, unexpected high frequency behavior is observed in simulations with an input signal up to 2 THz. © 2020 IEEE.

This paper discusses advances related to the integration of future mobile electronic THz systems. Without claiming to provide a comprehensive review of this surging research area, the authors gathered research on selected topics that are expected to be of relevance for the future exploration of components for practical mobile THz imaging and sensing applications. First, a brief technology review of integrated mobile THz components is given. Advances in III-V technology, silicon technology, and resonant-tunneling diodes (RTD) are discussed. Based on an RTD source and a SiGe-HBT direct detector, low-cost and compact computed tomography is presented for volumetric continuous-wave imaging at around 300 GHz. Moreover, aspects of system integration of mobile THz MIMO radars are discussed. Thereby, a novel phase-locked loop concept utilizing a high-stability yttrium-iron-garnet-tuned oscillator to synthesize ultra-stable reference mmWave signals is shown, and an adaptive self-interference cancellation algorithm for THz MIMO in the digital domain based on Kalman filter theory is proposed. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

This paper presents a 0.5 THz oscillator, realized using a transferred-substrate (TS) 0.3 μm InP DHBT process. It delivers -11 dBm peak output power. The DC consumption is only 15 mW from a 1.6 volts power supply, which corresponds to 0.5 % peak DC-to-RF efficiency. The oscillator exhibits the highest efficiency of a millimeter-wave frequency source beyond 400 GHz reported to date. The core area of the circuit is only 0.6 x 0.6 mm2, © 2019 European Microwave Association (EuMA).

The monolithic on-chip integration and design of a high current density InP-based Triple Barrier Resonant Tunneling Diode within a bow-tie antenna structure for detection application is presented. The asymmetrical current-voltage characteristics of the Triple Barrier Resonant Tunneling Diode and its small capacitance provide a powerful candidate for THz signal detection. The integration into a planar broadband antenna structure such as a bow-tie design enables realization of a broadband detector from single GHz up to THz frequencies. In this work, experimental data are demonstrated in the frequency range of 75 to 110 GHz and from 220 to 330 GHz. © 2019 IEEE

We report a method for analyzing and evaluating quantum transport parameters on the basis of our theoretical approach and experimental data in triple-barrier resonant tunneling diodes. Effective tunneling time and phase relaxation time are extracted from measured S-parameters with determination of parasitic components. © 2019 IEEE.

Common thermoelectric generators are based on the Seebeck effect, which describes the thermal diffusion of majority charge carriers within a temperature gradient in a solid. It is a unipolar transport phenomenon that gets suppressed if bipolar charge carriers occur. Here, we demonstrate by experiments that thermally excited bipolar charge carriers can be separated by the built-in field without external bias within a p-n junction. Such a phenomenon has been predicted theoretically before but was never proven experimentally. In the experiment, a nominal intrinsic silicon wafer (doping concentration less than 1013cm-3) was inserted in a p-i-n structure. It could be shown that electric power can be extracted from the space charge region (i-region), while the conventional thermoelectric contribution from the p-and n-regions is suppressed by short-circuiting. While the measured and simulated overall Seebeck effect of intrinsic silicon predicts a zero crossing of output power with increasing hot-side temperature due to a transition from p-type to n-type transport, the measured and simulated output power of the p-i-n structure increases monotonically with increasing hot-side temperature, indicating clearly the different nature of both mechanisms. © 2019 Author(s).

We present a novel approach to attain Ga-polar n-GaN nanowires on n-Si(111)/AlN templates, by site- and polarity-controlled metal organic vapor phase epitaxy. A three-stage process is developed to (i) form equally-sized Ga-polar GaN islands, (ii) change the growth direction towards the vertical direction and finally, to (iii) obtain continuous nanowire epitaxy. Homogeneous islands are achieved by minimizing parasitic nucleation and adjusting the adatom diffusion length to the used nanoimprint pattern. The influence of the carrier gas composition on the polarity is studied, achieving pure Ga-polarity by mostly using nitrogen carrier gas. Enhancing the Si/Ga-ratio leads to an amplification of the vertical growth, but also to a reduced number of NWs. 100% growth is attained by a height dependent V/III-ratio adjustment. The results are supported by a qualitative model, explaining how suppression of multi-pod, parasitic and inhomogeneous crystallization can be realized by trading off in situ SiNx passivation and localized GaN growth. © 2019 The Royal Society of Chemistry.

In this article we report on the development of nickel-chrome (NiCr) thin film resistors (TFRs) for application in an Indium Phosphide (InP) Hetero-Bipolar Transistor process. We developed a stable process with low specific contact resistance, in which the sputtered NiCr is structured by lift-off. We measured a specific contact resistance to NiCr of 8 ×10 −10 Ω ⋅ cm 2 . Furthermore we show the difficulties of structuring NiCr with an acid and connecting the NiCr from the top. Stress tests exhibited a high thermal resistance and high operation temperature of the NiCr on top of our BCB stack. Implemented NiCr resistors exhibit excellent agreement between simulation and measurement for high frequency applications. The utilization of the TFRs in microwave circuits showing excellent usability for microwave and terahertz applications. © 2019 Elsevier B.V.

We report on surface pretreatment for ohmic contacts to p-doped In0.53Ga0.47 As with improved thermal stability. It is found that the cleaning of In0.53Ga0.47 As surface by ammonium sulfide or sulfuric acid offers the optimum surface treatment prior to metal deposition. Contacts using an iridium contact layer and palladium diffusion barrier were fabricated and compared to a conventional platinum-based contact Pt/Ti/Pt/Au. Pt-based metal stack suffered from void formation and high reactivity with the semiconductor when annealed at 240 °C for a few hours, as examined by transmission electron microscopy. As a result, the Pt-based stack exhibited strong deterioration of the resistivity. On the other hand, the Ir contact maintained its integrity during thermal stress. The improved contact exhibited a void and reaction-free microstructure and offered stable resistivity values with annealing. © 2019 Elsevier B.V.

In this work the reduction of reverse currents in Au-catalyzed, MOVPE grown coaxial GaAs nanowire diodes are reported. The reduction is achieved by introducing an interstitial, lattice-matched i-InGaP shell (spacer) as tunneling barrier inside the junction, which also functions as a selective etch stop. With increasing spacer thickness, rectification ratios of &gt;1.57 × 106 at ± 1.65 V, ideality factors of 1.3, and dark saturation current densities as low as 20 pA cm−2 are extracted, which are related to a reduced tunneling probability. Temperature-dependent DC measurements of junctions with thin spacers show a correlation to a simple (trap-assisted) tunneling model. With absolute reverse currents in the pA range down to −3 V bias, the improved diode is implemented as a collector-base junction in a coaxial n(i)pn nanowire structure by growing an additional, outer n-doped InGaP shell as the emitter layer in a nanowire HBT. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

In this paper, a transmitarray element (TE) is designed for wireless subharmonic injection-locked triple barrier (TB) resonant tunneling diode (RTD) oscillators. It adopts a receiver antenna (RA)-transmitter antenna (TA) structure. The RA is a u-slotted patch antenna, and we use a cubic silicon block at top of this patch, so as to increases the RA gain and radiation efficiency. A fat monopole structure with a slot-like counterpoise is used as the TA. In this design, the RA can receive 100 GHz subharmonic injection signal (SIS). Meanwhile, the TA will radiate the 300 GHz fundamental oscillation signal (FOS) generated by the TB RTD. Moreover, the TA structure can isolate the 300 GHz FOS coming into the RA but couple the received 100 GHz SIS to the TB RTD, which performs like a filter-antenna. In the simulation, the transmission loss in the TA structure is higher than 15 dB around 300 GHz and only about 1.5 dB around 100 GHz. The gain of RA is 6 dBi with 65% radiation efficiency at 100 GHz and the gain of TA is 14 dBi at 300 GHz when applying a 1 mm radius silicon lens at the backside of the InP substrate. © 2019 IEEE.

Signal detection at (sub-)mm-wave frequencies via a single chip size component is discussed. The monolithic integration consists of high current density InP-based Triple Barrier Resonant Tunneling Diode into an on-chip antenna. The asymmetrical current voltage characteristic of the Triple Barrier Resonant Tunneling Diode enables signal detection at zero bias. A very high responsivity above 250 GHz is experimentally demonstrated. Low temperature DC rectification factor of the diode is investigated and a thermionic current contribution over the temperature is presented. © 2019 IMA - Institut fur Mikrowellen- und Antennentechnik e.V.

A broadband single-pole-double-throw (SPDT) switch is presented covering 220–325 GHz in 800 nm transferred substrate InP DHBT technology. The SPDT switch configuration employs shunt-topology. The circuit achieves an isolation of >36 dB within the band with very low DC power of 9 mW, benefitting from the low intrinsic capacitance of the transistors. This is the highest reported isolation for wideband SPDT switches covering 220–325 GHz. This three-stage SPDT switch also demonstrates the highest isolation of 12 dB per stage in this frequency range. © The Institution of Engineering and Technology 2018.

This paper presents a DC-95 GHz distributed amplifier (DA) based on an InP/GaAsSb/InP 800 nm DHBT technology. The circuit employs five cascode unit cells with 0.8 μm × 6 μm HBTs. To obtain flat small-signal gain and group delay characteristics, inductive peaking is used at the collector of the common-base transistor. The amplifier exhibits 12 dB gain from 1-100 GHz, with S11 and S22 below -10 dB throughout the frequency range. DC consumption is only 126 mW and group delay remains below 20 ps up to 65 GHz. The simulated saturated output power reaches 12 dBm with a variation of ±0.75 dB across the entire band of operation. This performance is very useful in high-speed, ultra-low power optical systems. © 2018 IMA.

This paper presents a W -band hetero-integrated transmitter module using InP-on-BiCMOS technology. It consists of a Phase Locked Loop (PLL) in 0.25 μm BiCMOS technology and a frequency multiplier followed by a double-balanced Gilbert mixer cell in 0.8 μm InP-HBT technology, which is integrated on top of the BiCMOS MMIC in a wafer-level BCB bonding process. The PLL operates from 45 GHz to 47 GHz and the module achieves a measured single sideband (SSB) power conversion loss of 20 dB and 22 dB at 88 GHz and 95 GHz, respectively, limited by the output power from the PLL source. The entire circuit consumes 434 mW DC power. The chip area of the module is 2.5×1.3 mm 2 , To the knowledge of the authors, this is the first complex hetero-Integrated module reported so far. © 2018 European Microwave Association - EuMA.

This letter presents a 1 to >110-GHz ultrawideband traveling-wave amplifier (TWA) based on 500-nm transferred-substrate InP double-heterojunction bipolar transistor technology. The HBT cells are realized with inductive peaking at the output and match the phase delay between individual stages. The collector bias is slightly below the value for the maximum current gain. This allows a frequency-invariant high-output power characteristic with a flat group delay. The amplifier exhibits a gain of 13 dB with a measured bandwidth of 1-110 GHz and a uniform 10-dBm 1-dB compression output power with an associated maximum PAE of 8% at 110 GHz. To the best of our knowledge, this is the highest PAE and the maximum flat output power reported for such a TWA covering frequencies up to 170 GHz. The amplifier consumes only 129 mW, which is among the lowest dc power dissipations reported for the given gain-bandwidth product. Moreover, the group delay is flat across the band, which makes the TWA very useful in high-speed optical communication systems. © 2001-2012 IEEE.

This paper reports an ultra-wideband low-noise amplifier in a transferred-substrate InP DHBT technology. The wideband characteristics are obtained by using a distributed topology with cascode unit cells. Each unit cell consists of two cascode-connected transistors with 500 nm emitter length and an f-{t/}f-{max} of ∼ 350/400 GHz respectively. Due to optimum line-impedance matching, low common-base transistor's capacitance, and low collector-current operation, the circuit also exhibits a low noise figure. The measured circuit shows a bandwidth of 40... 185 GHz with a noise figure of 8 dB in the frequency range 75... 105 GHz. Moreover, this circuit demonstrates the widest 3-dB bandwidth operation among all reported single stage amplifiers with cascode configuration. © 2018 European Microwave Association.

In this paper, an electromagnetic (EM) simulation assisted parameter extraction procedure is demonstrated for accurate modeling of down-scaled transferred-substrate InP HBTs. The external parasitic network associated with via transitions and device electrodes is carefully extracted from calibrated three-dimensional EM simulations up to 325 GHz. Following an on-wafer multi-line Through-Reflect-Line calibration procedure, the external parasitic network is de-embedded from the transistor measurements and the active device parameters are extracted in a reliable way. The small-signal model structure augmented with the distributed parasitic network provides accurate small-signal prediction up to 220 GHz. © 2018 Cambridge University Press and the European Microwave Association.

Local oscillator signal generation with low phase-noise is an important topic for future communications systems operating in D-band and beyond. This paper presents a D-band fundamental reflection-type source with high DC-to-RF efficiency and low phase-noise properties, realized using a transferred-substrate (TS) mathbf{0.8} mu mathbf{m} InP-DHBT process. It delivers 9.5 dBm peak output power, with 2 GHz tuning range. The DC consumption is only 43.5 mW from a single 2.5 volts power supply, which corresponds to 20 % peak DC-to-RF efficiency. The measured single side band (SSB) phase noise reaches -94 dBc/Hz and -115 dBc/Hz at 1 MHz and 10 MHz offset frequency, respectively. To the knowledge of the authors, this is the highest DC-to-RF efficiency reported so far in this frequency range with excellent phase noise performance and state-of-the-art output power. © 2018 European Microwave Association.

Signal generation and detection at mm-wave frequencies via a single chip size component is demonstrated. The monolithic integration consists of high current density Triple Barrier Resonant Tunneling Diode into a slot antenna. The asymmetrical current voltage characteristic of the Triple Barrier Resonant Tunneling Diode enables signal detection at zero bias and signal generation at forward bias within the regime of negative resistance. Signal generation and detection at above 250 GHz are experimentally demonstrated. © 2018 IEEE.

A site- and polarity-controlled MOVPE growth of 3D-GaN on Si(111) substrates is established using the polarity-dependent growth speed of GaN on an intermediate AlN layer. For hydrogenated Si or elevated AlN growth temperatures mixed-polar growth is observed. N-polarity could be realized on oxidized Si(111) surfaces by a reduced AlN growth temperature of TAlN = 930 °C. Specific Si crystal facets (e.g., {100}, {112}) are determined as starting points for metal-polar growth of AlN. By site-controlled etching in Si, we intentionally expose these additional crystal facets prior to epitaxy to obtain defined starting points for metal-polar growth. At TAlN = 930 °C, this leads to a site-controlled growth of metal-polar GaN, surrounded by N-polar AlN on Si(111). Thus both, a polarity- and site-controlled epitaxial growth of 3D-GaN is achieved. The new developed method has been applied to a large variety of structure sizes from 650 nm to 1 mm. The results are supported by a schematic model, explaining the influence of surface termination, in situ desorption, and growth conditions. This paves the way to the development of future 3D-opto-electronic devices, directly established on Si. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

We report on the realization mymargin of transferred-substrate InP/GaAsSb double heterostructure bipolar transistors in a terahertz monolithic integrated circuit process. Transistors with 0.4- mu m -wide single emitters reached unilateral gain cutoff frequencies of around 530 GHz with simultaneous current gain cutoff frequencies above 350 GHz. Extrinsic collector capacitance is effectively reduced in the transfer-substrate process. In combination with the high collector breakdown voltage in the InP/GaAsSb heterobipolar transistor structure of 5 V, this process is amenable to analog power applications at millimeter (mm-wave) and sub-mm-wave frequencies. We demonstrate reliable extraction procedures for unilateral gain and current gain cutoff frequencies. © 1963-2012 IEEE.

This paper presents an active up-converter realized as hetero-integrated module in InP-on-BiCMOS technology. It consists of a fundamental Voltage Controlled Oscillator (VCO) in 0.25 μm BiCMOS technology and a frequency multiplier followed by double balanced Gilbert mixer cell in 0.8 μm transferred substrate (TS) InP-HBT technology, which is integrated on top of the BiCMOS MMIC. The fundamental VCO operates at 54 GHz. The module achieves a single-sideband (SSB) power up-conversion gain of 2.5 dB and -3.5 dB at 82 GHz and 106 GHz, respectively. It exhibits > 25 GHz IF bandwidth. To the knowledge of the authors, this is the first heterointegrated module reported so far. © 2017 IEEE.

This paper presents for the first time high-efficiency W-band power amplifiers (PAs), the design of which follows the digital PA (DPA) design concept. Two DPAs with different output networks have been realized: A single-band version (S-DPA) for 95 GHz and a dual-band design (D-DPA) for signal frequencies fS of 68 GHz (first band) and 76 GHz (second band), respectively. The PAs are realized as monolithic microwave-integrated circuits (MMICs) in a 0.8 μm InP DHBT transferred-substrate process. They utilize a double-emitter-finger DHBT unit cell with an emitter area of 2 × 0.8 × 6 μm3 each. In contrast to the usual W-band PAs, the proposed single-stage amplifier MMICs do not apply any special reactive matching for the transistor, which leads to very compact chip sizes of 0.27 mm2 (S-DPA) and 0.39 mm2(D-DPA). The S-DPA includes one band-pass filter (BPF) at the output with 0.6 dB insertion loss (IL) and 24 dB input return loss (RL) at the signal frequency of 95 GHz. The dual-band BPF shows 0.7 dB IL in both bands with a RL of more than 21 dB each. Applying an overdriven sinusoidal input signal to emulate digital operation the DPAs achieve a maximum output power of 14.4 dBm and power-added efficiency of 31% when using the single-band configuration. Collector efficiencies of more than 80% and the flexible multi-band operation demonstrated prove the great potential of the digital PA concept for future high-speed communications. © 2017 Cambridge University Press and the European Microwave Association.

In this paper an electromagnetic (EM) simulation assisted parameters extraction procedure is demonstrated for accurate modeling of down-scaled transferred-substrate InP HBTs. The external parasitic network associated with via transitions and device electrodes is carefully extracted from calibrated 3D EM simulations up to 325 GHz. Following an on-wafer multi-line Through-Reflect-Line (TRL) calibration procedure, the external parasitic network is de-embedded from the transistor measurements and the active device parameters are extracted in a reliable way. The small-signal model structure augmented with the distributed parasitic network is verified against measured S-parameters up to 110 GHz. © 2017 European Microwave Association.

This paper presents the design and characterization of a broadband transition in the range dc to 500 GHz using the flip-chip concept. The extremely wideband performance is attained by optimizations in both process technology and electromagnetic design. On the process technology side, a thin-film process with scaled dimensions of 10 μ for via diameter and 2 μ bump height is employed for the chip and the carrier substrate. On the electromagnetic side, in addition to impedance matching, a detailed analysis of parasitic modes is considered for the design. The measurement results show less than 0.9-dB insertion loss per transition at 500 GHz and reflections below -18 dB over the entire dc to 500 GHz band. © 1963-2012 IEEE.

We developed a chip mounting technology suitable for low-cost assemblies in the 300-500-GHz frequency range, compatible with standard chip and submount fabrication techniques. The waveguide and transition designs are compatible with indium phosphide heterobipolar transistor millimeter-wave monolithic integrated circuit chip architecture. Increased conductor shielding in different multilayer thin-film waveguide topologies is applied to suppress radiative losses, enabling low-loss interconnects up to 500-GHz bandwidth. Standard flip-chip align-and-place equipment is used to assemble the chips onto submounts. Losses are evaluated by banded ${S}$ -parameter measurements between 10 MHz and 500 GHz. For an optimized stripline-to-stripline transition, an insertion loss of less than 1 dB was measured at 500 GHz. © 2017 IEEE.

This paper addresses noise modeling of transfersubstrate indium phosphide double heterobipolar transistors (InP DHBTs). Transistors with an emitter area of 0.8 × 6 μm2 (single-finger) and 2 × 0.8 × 6 μm2 (double-finger) are measured and simulated. It turns out that the correlation of shot-noise sources is negligible for these devices, although it was found in earlier works to be essential to describe GaAs HBT noise behavior. As a result, the work provides the basis for reliable extrapolation of noise performance beyond the frequency range provided by standard noise measurement equipment. © 2017 IEEE.

This paper presents the performance study of a 248 GHz voltage-controlled hetero-integrated signal source using indium phosphide (InP)-on-bipolar complementary metal-oxide-semiconductor (BiCMOS) technology. The source consists of a voltage controlled oscillator (VCO) in 0.25 μm BiCMOS technology and a frequency multiplier in 0.8 μm transferred-substrate InP-heterojunction bipolar transistor technology, which is integrated on top of the BiCMOS monolithic microwave integrated circuit in a wafer-level based benzocyclobutene bonding process. The vertical transitions from BiCMOS to InP in this process exhibit broadband properties with insertion losses below 0.5 dB up to 325 GHz. The VCO operates at 82.7 GHz with an output power of 6 dBm and the combined circuit delivers -9 dBm at 248 GHz with 1.22% tuning range. The phase noise of the combined circuit is -85 dBc/Hz at 1 MHz offset. The measured output return loss of the hetero-integrated source is >10 dB within a broad frequency range. This result shows the potential of the hetero integrated process for THz frequencies. © 2015 Cambridge University Press and the European Microwave Association.

The push to conquer the sparsely used electromagnetic spectrum between 100 and 1,000 GHz, commonly known as the millimeter-wave (mmW) and sub-mmW regions, is now in full force. The current rapid development of electronic circuits and subsystems beyond 100 GHz is enabled by improvements in high-frequency semiconductor technology and packaging techniques. In this article, we highlight recent advances we have developed in heterogeneous semiconductor-material chip integration for application toward the mmW frequency bands-in essence, a waferlevel integration approach that replaces chip-to-chip connections with monolithic integration. © 2017 IEEE.

A 96-GHz fixed-frequency fundamental oscillator with high efficiency is presented, realized using a transferredsubstrate (TS) 0.8 μm InP-DHBT process. It delivers 9 dBm output power, with phase noise values of -90 dBc/Hz and -118 dBc/Hz at 1 MHz and 10 MHz offset frequency, respectively. DC consumption is only 30 mW from a 1.6 volts power supply, which corresponds to the highest overall DC-to-RF efficiency of a millimeter-wave frequency source reported to date. © 2016 EuMA.

A power amplifier in 800 nm transferred-substrate InP DHBT technology is presented in this paper. The technology used in this work features an integrated diamond heat sink layer that has significant impact on the reduction of thermal resistance. This increases the DC-power limit as well as RF output power for the same transistor periphery. The power amplifier delivers 200 mW output power at 87 GHz, for a total emitter periphery of 96 μm, at a peak PAE of 20 % and for more than 25 GHz 3-dB bandwidth. © 2016 IEEE.

A 315-GHz reflection-type push-push oscillator is presented. It is realized using a 0.8 μm-emitter transferredsubstrate (TS) InP-DHBT technology with an fmax of 320 GHz. The oscillator delivers -10 dBm output power. DC consumption is only 21 mW from a 1.6 volts power supply, which corresponds to 0.5 % overall DC-to-RF efficiency. © 2016 EuMA.

This paper presents a wideband 330 GHz frequency quadrupler using 0.8 μm transferred substrate (TS) InP-HBT technology. The process includes a heat-spreading diamond layer, which improves the power handling capability of the circuit. The quadrupler delivers -7 dBm output power at 325 GHz, at a DC consumption of only 40 mW, which corresponds to 0.5 % of efficiency. It achieves 90 GHz bandwidth and exhibits very low unwanted harmonics. The circuit utilizes a balanced architecture. The results demonstrate the potential of the InP TS. © 2016 IEEE.

This letter presents a G-band balanced frequency doubler with high output power, realized using a 800 nm transferred-substrate InP-HBT process. The doubler delivers dBm in the range 140-220 GHz. The dc consumption is only 41 mW. To the knowledge of the authors, this is the highest output power for a wideband transistor based frequency doubler in the 140-220 GHz frequency range published so far. The results show the ability to implement a high output power G-band source in transferred-substrate InP HBT technology. © 2015 IEEE. Personal.

This paper presents for the first time a high-efficiency W-band power amplifier (PA), the design of which follows the digital PA (DPA) design concept. The PA is realized as MMIC in a 0.8 μm InP DHBT transferred-substrate (TS) process. It utilizes a double-emitter-finger DHBT unit cell with an emitter area of 2 × 0.8 × 6 μm2. In contrast to the usual W-band PAs the single-stage DPA MMIC does not apply any special reactive matching for the transistor, which leads to a very compact chip size of 0.27 mm2. It includes a band-pass filter (BPF) at the output with 0.6 dB insertion loss and 24 dB input return loss at the signal frequency of 95 GHz. Applying an overdriven sinusoidal input signal the DPA achieves a maximum output power of 14.4 dBm and a power-added efficiency (PAE) of 31%. Collector efficiencies of more than 80% demonstrate the great potential of the digital PA concept for future high-speed communications. © 2016 European Microwave Association.

In this paper, balanced G-band Gm-boosted frequency doublers in transferred substrate (TS) InP HBT technology are reported for the first time. The Gm-boosted frequency doublers consist of a phase compensated Marchand balun, Gm-boosted doubler stage, and an optional cascode gain stage at the output. The doubler without cascode demonstrates a maximum output power of +4.7 dBm around a narrow frequency range at 200 GHz when driven with an input power of +10 dBm. A Gm-boosted frequency doubler with cascode demonstrates an output power of +5.4 dBm at 190 GHz when driven with an input power of +11 dBm. The power consumptions of the Gm-boosted frequency doubler without and with cascode are 30.9 mW and 56.4 mW, respectively. The fundamental suppression for both doublers remains better than 17.3 dB over an input frequency range of 75-110 GHz. © 2016 European Microwave Association.

In this article we report on the reduction of redeposition during inductively coupled plasma (ICP) etching of benzocyclobutene (BCB) with a soft mask in a sulfur hexafluoride/oxygen (SF6/O2) plasma. We have developed an anisotropic ICP recipe to fabricate vertical interconnects through BCB for our indium phosphide (InP) transferred-substrate DHBT technology. In this context the new recipe has an etch inhomogeneity on 3 in. wafer of &lt; 1% 3-sigma based on the total BCB thickness. The origin of residuals post resist ashing consisting of Al, F, and O was traced back to reactor chamber parts made from Al2O3. The amount of redeposition appears to be minimized with lower chamber pressure. We saw an impact of different substrate carrier materials on the amount of redeposition, etch rate, and bias. Remaining deposits could be removed in a wet chemical final rinse, which was based on diluted tetramethylammonium hydroxide (TMAH). With the new high density plasma recipe the BCB etch rate could be increased fivefold while maintaining excellent lateral structure fidelity and minimizing etch byproduct redeposition. © 2016 Elsevier B.V.

The RF power output of scaled subterahertz and terahertz indium phosphide double-heterostructure bipolar transistors (InP DHBTs) is limited by the thermal device resistance, which increases with the geometrical frequency scaling of these devices. We present a diamond thin-film heat sink process aimed at the efficient removal of the heat generated in submicrometer InP HBTs. The thin-film diamond is integrated in a wafer bond process. Vertical connections are facilitated by plasma-processed contact holes through the diamond layer, metallized with electroplated gold. The process is suitable for monolithic circuit integration, amenable to the realization of high-power analog circuits in the millimeter-wave region and beyond. The thermal resistance of double-finger transistors with a 0.8- emitter width could be reduced to 0.7 K/mW, while reaching the gain cutoff frequencies of GHz and =350 GHz. An integrated two-stage power amplifier with four-way power combining fabricated in this technology exhibited 20-dBm power output at 90 GHz with a bandwidth of 10 GHz. © 1963-2012 IEEE.

We present a wafer-level heterointegrated indium phosphide double heterobipolar transistor on silicon germanium bipolar-complementary metal oxide semiconductor (InP DHBT on SiGe BiCMOS) process which relies on adhesive wafer bonding. Subcircuits are co-designed in both technologies, SiGe BiCMOS and InP DHBT, with more than 300 GHz bandwidth microstrip interconnects. The 250 nm SiGe HBTs offer cutoff frequencies around 200 GHz, the 800 nm InP DHBTs exceed 350 GHz. Heterointegrated signal sources are demonstrated including a 328 GHz quadrupling source with -12 dBm RF output power. A common design kit for full InP DHBT/SiGe BiCMOS co-design was set up. The technology is being opened to third-party customers through IHP's multi-purpose wafer foundry interface. Microphotograph of InP DHBT / SiGe BiCMOS wafer. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

This paper presents a 250 GHz hetero-integrated VCO using InP-on-BiCMOS technology. It consists of a single-ended Colpitts Voltage Controlled Oscillator (VCO) in 0.25 μm SiGe-BiCMOS technology and a common-emitter based frequency tripler in 0.8 μm transferred-substrate (TS) InP-HBT technology, which are combined using a wafer-level BCB bonding process. The VCO operates at 83 GHz and the combined circuit delivers 0.7 mW output power at 250 GHz with 2% tuning range. This result documents recent advances of the hetero integrated process towards THz frequencies. © 2015 EuMA.

This paper presents a 330 GHz hetero-integrated signal source using InP-on-BiCMOS technology. It consists of a fundamental Voltage Controlled Oscillator (VCO) in 0.25 μm BiCMOS technology and a frequency quadrupler in 0.8 μm transferred substrate (TS) InP-HBT technology, which is integrated on top of the BiCMOS MMIC in a wafer-level BCB bonding process. The fundamental VCO operates at 82 GHz and the combined source delivers -12 dBm output power at 328 GHz. To the knowledge of the authors, this is the first hetero-integrated signal source in the frequency range beyond 300 GHz reported so far. It demonstrates the potential of the hetero-integration process for THz frequencies. © 2015 IEEE.

This paper presents a single-ended efficient 290 GHz harmonic oscillator, realized using 0.8 μm transferred-substrate (TS) InP-DHBT technology. The architecture of this oscillator is based on a third harmonic generation from a fundamental differential cross-coupled topology. The oscillator delivers-8.5 dBm output power. DC consumption is only 28 mW from a 1.5 volts power supply, which corresponds to 0.5 % overall DC-To-RF efficiency. To the authors' knowledge, this is the highest DC-To-RF efficiency harmonic oscillator beyond the 220 GHz frequency band published so far. © 2015 EuMA.

With the increasing availability of MMICs at frequencies beyond 100 GHz low-loss interconnects for module fabrication in this frequency range become essential. This letter presents results on a flip-chip mounting approach exhibiting a bandwidth of more than 250 GHz, supporting both coplanar and stripline transitions. The interconnects are realized with 10 μm-diameter AuSn microbumps. S-parameter measurements show an insertion loss of less than 1.0 dB per interconnect and a return loss better than 10 dB up to 250 GHz. The experimental results are in good agreement with 3-D EM simulations. © 2001-2012 IEEE.

A G-band broadband frequency doubler based on InP transferred-substrate (TS) InP-DHBT technology is presented. The MMIC utilizes a two 2-finger HBTs with a total emitter size of 4 × 0.8 × 5 μm2. Total chip size is 0.9 × 0.78 mm2. The doubler delivers a maximum output power of 10 dBm at 160 GHz. At the same frequency, the circuit exhibits a conversion gain up to 4 dB and a maximum output efficiency of 14 % for a total DC consumption of 72 mW. Output power stays above 7 dBm from 140 to 180 GHz, which yields a 3-dB bandwidth of 40 GHz. The positive gain values demonstrate the inherent advantage of active multipliers against their passive counterparts. © 2015 EuMA.

A method to improve the thermal management of indium phosphide (InP) double-hetero bipolar transistors (DHBTs) fabricated in a transferred- substrate technology is presented. A vapour-phase deposited diamond layer acting as a heat spreader is heterogeneously integrated into the vertical layer stack. It is observed that the diamond layer reduces the thermal resistance of a 0.8 × 5 μm2 single emitter-finger HBT by roughly 75% down to 1.1 K/mW which is, to the authors' knowledge, the best value reported thus far for InP HBTs of comparable size. It is also the first demonstration of heterogeneous integration of diamond into an InP HBT monolithic microwave integrated circuit. © 2015 The Institution of Engineering and Technology.

The design margins for sub-mm-wave flip-chip transitions in three different topologies, coplanar-to-coplanar, stripline-to-coplanar, and stripline-to-stripline, were verified with the realization and S-parameter measurement of passive chip assemblies, which contain the same wiring architecture as our InP DHBT circuit integration. High yield was observed, and less than 2 dB insertion loss per transition was measured above 300 GHz on the stripline-to-stripline design. © 2015 IEEE.

We introduce an approach that combines a 3' InP-DHBT transferred-substrate process with a SiGe-BiCMOS process. First, silicon and InP wafers are processed separately in different fabs. The silicon wafer runs through the complete 0.25 μm BiCMOS production process with five metal layers aluminum/tungsten back-end-of-line using silicon dioxide as dielectric. The processing was adapted for the following wafer bond process by planarization of the topmost metal level. This process flow was improved by using a SiN CMP stop layer on top of the metal layer stack, comparable to trench fill planarization. In that way a low surface topography was reached, this guarantees proper bonding results. Different mm-wave circuits operating at frequencies up to 246 GHz were produced to demonstrate the capability of the process flow. © 2014 IEEE.

A 270-GHz reflection-type push-push oscillator is presented, realized using 0.8μm emitter InP-DHBTs. The InP DHBT-on-BiCMOS offers both InP HBT and BiCMOS technologies but in this case only the InP part is used. The transistors exhibit a maximum oscillation frequency f<inf>max</inf> of 300 GHz. The oscillator delivers -9.5 dBm output power. DC consumption is only 31 mW from a 1.8 volts power supply, which corresponds to 0.4 % overall DC-to-RF efficiency. © 2014 European Microwave Association.

Applications such as radar imaging and wideband communications are driving the research on millimeter-wave circuits. For some applications SiGe hetero junction bipolar transistors (HBTs) are limited in output power. III-V technologies (like InP) can realize devices showing a high product of peak transit frequency multiplied with the open base breakdown voltage. Therefore, merging the qualities of both III-V and Si technology will enable a new class of high-performance ICs. Our approach combines an InP-DHBT transferred-substrate process with a Si-BiCMOS process. The key method is an aligned face-to-face wafer bonding with a subsequent removal of the InP substrate. Different integrated signal sources with an output frequency up to 246 GHz were designed and produced using different combinations of BiCMOS and InP circuit building blocks to demonstrate the capabilities of the heterointegration routine. In this paper the influences of the wafer bonding and the finalization of the InP-DHBT process on SiGe devices were investigated. It was found that the influences on the BiCMOS devices were rather small. © The Electrochemical Society.

Recent advances in MMIC technology have opened the possibilities for circuit operation in the THz range. There are numerous examples of BiCMOS and III-V compound device technologies with demonstrated performance beyond 600 GHz. Characterization of such MMIC are predominantly performed on-wafer in a planar environment. However, on-wafer characterization facilities do not fully keep pace with MMIC development in terms of frequency and power. The paper discusses issues involved in on-wafer calibration at mm-wave frequencies, which is the basis for accurate measurements and characterization of active and passive device. Subsequently, the paper discusses mm-wave interconnect characterization. Low-loss interconnects are important for mm-wave MMIC, especially in case of heterogeneous integration. Finally, a novel heterogeneous integration approach of bipolar technologies, using both BiCMOS and InP DHBT processes is presented. This approach heavily relies on low-loss interconnects and accurate device modelling. It will be shown that accurate large-signal models can be efficiently extracted from well-calibrated on-wafer multi-bias small-signal measurements, but verification is difficult due to calibration difficulties at mm-wave frequencies. © 2014 IEEE.

In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing a direct parameter extraction methodology dedicated to III-V based HBTs. It is shown that the modeling of measured S-parameters can be improved in the millimeter-wave frequency range by augmenting the small-signal model with a description of AC current crowding. The extracted elements of the small-signal model structure are employed as a starting point for the extraction of a large-signal model. The developed large-signal model for the TS-HBTs accurately predicts the DC over temperature and small-signal performance over bias as well as the large-signal performance at millimeter-wave frequencies. © Cambridge University Press and the European Microwave Association 2014.

In order to benefit from the material properties of both InP-HBT and SiGe-BiCMOS technologies we have employed three-dimensional (3D) Benzocyclobutene (BCB)-based wafer bonding integration scheme. A monolithic wafer fabrication process based on transfer-substrate technology was developed, enabling the realization of complex hetero-integrated high-frequency circuits. Miniaturized vertical interconnects (vias) with low insertion loss and excellent broadband properties enable seamless transition between the InP and BiCMOS sub-circuits. © 2013 Elsevier B.V. All rights reserved.

This work presents a novel InP DHBT-SiGe BiCMOS technology platform by wafer-scale heterogeneous integration. The technology provides vertical stacking of processed InP DHBT wafers directly on top of processed BiCMOS wafer with low-loss ultrabroadband interconnects up to 200 GHz. We demonstrate first MMIC operating up to 300 GHz. © 2013 IEEE.

We demonstrated an integrated InP high-power dual pair balanced uni-traveling carrier photo-detector. Each pair delivers over 1 W of RF output power into a 50 Ω load at 2 GHz which is 6 dB higher than a discrete diode of the same junction diameter. The responsivity is 0.65 A/W and the common mode rejection ratio of the balanced diode pair was measured to be greater than 40 dB. The OIP3 was measured to be 48 dBm for one balanced pair of diodes. This balanced dual pair photo-detector is very well suited for enhancing the performance of coherent analog microwave photonic links. © 2011 IEEE.

We realized a monolithic dual-polarization dual-quadrature coherent receiver with balanced detection on InP using a single epitaxial step. It monolithically integrates the polarization splitters, 90° hybrids, and balanced photodiodes in 4.1 mm2. We demonstrate reception of 112-Gb/s polarization-division-multiplexed quadrature phase-shift keying with 17.3-dB optical signal-to-noise ratio at 10 -3 bit-error rate. © 2011 IEEE.

We demonstrate an efficient coupler on InP using an etched grating on a suspended InGaAsP membrane. We measure a peak coupling efficiency of 40% (-4 dB) between a cleaved standard single-mode fiber and a conventional nonsuspended InGaAsP waveguide with a 3-dB bandwidth of ∼45 nm. © 2010 IEEE.