Atomic/molecular layer deposition of luminescent inorganic-organic hybrid erbium pyridine dicarboxylate thin films

Lukas Mai, Inorganic Materials Chemistry, Ruhr-University Bochum, Bochum, Germany
Zivile Giedraityte, Department of Chemistry, Aalto University, Helsinki, Finland
Marcel Schmidt, Applied Solid-State Physics, Ruhr-University Bochum, Bochum, Germany
Detlef Rogalla, RUBION, Ruhr-University Bochum, Bochum, Germany
Sven Scholz, Applied Solid-State Physics, Ruhr-University Bochum, Bochum, Germany
Andreas D. Wieck, Applied Solid-State Physics, Ruhr-University Bochum, Bochum, Germany
Maarit Karppinen, Department of chemistry, Aalto University, Helsinki, Finland
Anjana Devi, Inorganic Materials Chemistry, Ruhr-University Bochum, Bochum, Germany

Within this work, the successful combination of tris(N,N’-diisopropyl-2-dimethylamido guanidinato)erbium(III) ([Er(DPDMG)3]) and 3,5-PDA in an ALD/MLD process is presented. The usage of the guanidinate precursor resulted in high growth rates compared to common rare earth precursors, such as beta-diketonates ([Er(THD)3]). Furthermore, we investigated the typical ALD characteristics, proving a true ALD/MLD process. From Rutherford-Backscattering spectometry (RBS) experiments, nearly stoichiometric erbium 3,5-pyridine dicarboxylate ([Er2(3,5-PDC)3]) was found to be deposited. The reaction between the precursors by deprotonation of 3,5-PDA and subsequent coordination of the nitrogen functionality towards the erbium-ion was confirmed by FT-IR spectroscopy. From UV-Vis investigation, a strong absorption at 270 nm was detected and assigned to the absorption of the organic molecule. Furthermore, by direct excitation of different electronic states of the erbium ions, a sharp photoluminescence emission at 1535 nm arises. Here, intensity could be increased with decreasing erbium concentration which in this case is dependent on the deposition temperature. The obtained results show the distinct advantage of using a well-developed inorganic precursor such as [Er(DPDMG)3] in combination with different organic molecules for ALD/MLD processes in order to produce novel materials that can be precisely tailored for various applications.

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