High Mobility Nanocrystalline Silicon TFTs for Display Application

Abstract

AbstractNanocrystalline silicon (nc-Si) thin film transistors (TFTs) of which active layer thickness was 100nm were fabricated using inductively coupled plasma chemical vapor deposition (ICP-CVD) at 150°C. The fabricated nc-Si TFT exhibits rather high field effect mobility exceeding 22cm2/Vs and excellent sub-threshold slope of 0.45V/dec. The nc-Si film deposited 150°C as an active layer of the TFT shows high crystallinity more than 70% and very thin incubation layer less than 20nm. ICP-CVD provides high density plasma with reduced ion bombardment during the deposition on nc-Si and He dilution can enhance the decomposition of SiH4 into Si, SiHX radicals and atomic H, so that high quality nc-Si film can be fabricated. The gate insulator SiO2 film deposited by ICP-CVD at 150°C shows good electrical characteristics such as flat band voltage of -1.8V and breakdown voltage of 6.2MV/cm.