Thin-film transistors with multistep deposited amorphous silicon layers

Abstract

Inverted, staggered thin-film transistors (TFTs), in which the a-Si:H layer is deposited stepwise, using different rf powers, were prepared and studied. Using identically prepared top and bottom interface silicon layers, the multilayer a-Si:H TFT characteristics can be better or worse than those of a single-layer a-SiH TFT, depending on the rf power used to deposit the middle layer and the total number of layers added. The result can be explained by considering the mechanism of the SiH4 plasma deposition process. For example, the extra hydrogen generated in the high power plasma can passivate dangling bonds, which enhances the transistor performance. The high intensity plasma radiation source can generate defects at the film/film interface as well as in the bulk of the film, which deteriorates the transistor.© 1995 American Institute of Physics.