High-mobility Nanocrystalline Indium Oxide TFTs with Silicon Nitride Gate Dielectric

Abstract

ABSTRACTA 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 foundry-compatible 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.