Effects of Back-Channel Etching on the Performance of a-Si:H Thin-Film Transistors

Thickness of the a-Si:H layer in the back-channel etched thin film transistor (TFT) was successfully reduced to less than 100 nm, with an accompanying increase in the field effect mobility. The thinning was realized by reducing surface defects of the a-Si:H layer generated in the back-channel overetching step. The relationships between the TFT performance and surface defects, analyzed by spectroscopic ellipsometry, were investigated as a function of a-Si:H thickness and back-channel etching depth.