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1074-I05-35

High-mobility Nanocrystalline Indium Oxide TFTs with Silicon Nitride Gate Dielectric Kai Wang1, Yuriy Vygranenko2, and Arokia Nathan3 1 Electrical and Computer Engineering, University of Waterloo, 200 University Ave. West, Waterloo, N2L 2G1, Canada 2 Department of Electronics Telecommunications and Computer, ISEL, Lisbon, P-1949-014, Portugal 3 London Centre for Nanotechnology, University College London, London, WC1H 0AH, United Kingdom

ABSTRACT A variety of oxide semiconductors such as ZnO, SnO2, In2O3 and other multi-component oxide compounds have been successfully used as channel materials in thin-film transistors (TFTs). Compared with amorphous silicon and organic semiconductor counterparts, the unique features of these materials include good performance, stability, low temperature processing, and transparency. In this work, we report on room-temperature deposition of indium oxide thin films by reactive ion beam assisted evaporation (IBAE) and their application to TFTs. By modifying the deposition parameters, nanocrystalline indium oxide (nc-In2O3) with an average grain size of 12 nm was achieved. TFTs with IBAE nc-In2O3 channel and silicon nitride gate dielectric deposited by conventional plasma-enhanced chemical vapour deposition (PECVD), were fabricated. The n-channel TFT has a threshold voltage of ~2.5 V, a field-effect mobility of ~32 cm2/Vs, along with an ON/OFF current ratio of ~108, and a sub-threshold slope of 2.5 V/decade. The TFT reported here has one of the best performance characteristics in terms of device mobility, ON/OFF current ratio, and OFF current, using conventional, and large area foundrycompatible PECVD gate dielectrics. The device performance coupled with its low-temperature processing makes IBAE-derived nc-In2O3 TFT a promising candidate for active matrix flat panel displays. INTRODUCTION Since the invention of the first transparent thin-film transistors made by ZnO thin films 1, transparent oxide semiconductor (TOS) based TFTs have become one of the most nascent and attractive research areas in thin film electronics. The continuous efforts have been taken to fabricate TFTs with zinc oxide 4, 5, tin oxide 6, indium oxide 7-9 as well as binary or ternary oxide compounds such as zinc-tin oxide 10, 11, zinc-indium oxide 12, zinc-indium-tin oxide 13, and indium-gallium-zinc oxide 14-17.The achieved field-effect mobility of those TFTs was generally in a range of 10~30 cm2/Vs. Compared with silicon and organic counterparts, TOS TFTs have much higher field-effect mobility leading to higher drain current density which is desirable for current-driven organic light emitting diode (OLED) displays. Furthermore, low temperature process makes these materials compatible with future generation of large area electronics that requires flexible substrates 14. With the continuous research and development, TOS TFT 3

technology is believed to be a promising alternative to the existing TFT technologies such as poly-Si, μc-Si, a-Si:H, and Organic TFTs. A gate dielectric with low defect density,