Y2O3 sol-gel passivation layer for solution-processed metal-oxide thin-film transistors

Conference: Mikro-Nano-Integration - 7. GMM-Workshop
10/22/2018 - 10/23/2018 at Dortmund, Deutschland

Proceedings: GMM-Fb. 92: Mikro-Nano-Integration

Pages: 6Language: englishTyp: PDF

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Subasi, Ersoy; Kunze, Ulrich (Ruhr University Bochum, Faculty of Electrical Engineering and Information Technology, Electronic Materials and Nanoelectronics, Bochum, Germany)
Boysen, Nils; Mai, Lukas; Devi, Anjana (Ruhr University Bochum, Faculty of Chemistry and Biochemistry, Inorganic Materials Chemistry II, Bochum, Germany)
Pham, Duy-Vu (Evonik Resource Efficiency GmbH, Electronic Solutions, Marl, Germany)
Bock, Claudia (Ruhr University Bochum, Faculty of Electrical Engineering and Information Technology, Microsystems Technology, Bochum, Germany)

In this study the electrical stability of solution processed metal-oxide thin-film transistors (MOTFTs) is improved by an yttrium oxide (Y2O3) passivation layer. Therefore, we tailored a simple Y2O3 sol-gel process towards a thin, smooth and continuous film. For a 0.1 M Yttrium(III) nitrate hexahydrate solution gelatinized for 5 h, pre-converted in an UV/O3 cleaner (t = 40 min) and thermally converted at T = 350 °C a root-mean-square (RMS) roughness of 0.1 nm is determined. The refractive index is 1.9 and corresponds to the reported value in literature (n = 1.9 [1]). Finally, we compare MOTFTs passivated by a) octadecylphosphonic acid (ODPA), b) the sol-gel derived Y2O3 and c) an Y2O3 layer from atomic layer deposition (ALD). The field-effect mobility is not significantly affected by the passivation layer and the onset voltage of MOTFTs passivated with a sol-gel derived Y2O3 layer amounts desirable 0 V. The onset voltage shift during negative-bias-stress (NBS) amounts to DeltaVon,Y2O3 = −2 V for MOTFTs with a sol-gel Y2O3 passivation layer and is five times smaller compared to MOTFTs with a solution-processed ODPA passivation layer (DeltaVon,ODPA = −10 V). The quality is comparable to MOTFTs passivated by Y2O3 with a cost-intensive ALD process (DeltaVon,ALD = −2 V).