Urbach energy dependence of the stability in amorphous silicon thin-film transistors

Abstract

We investigate the relationship between the stability of amorphous siliconthin-film transistors (a- Si:H TFTs) and the bulk properties of a- Si:H films. Threshold voltage shifts in a- Si:H TFTs are characterized by the thermalization energy E th for different times and temperatures and fitted by {1+ exp [(E th −E a )/kT 0 ]} −2 . We find that kT 0 exhibits a clear correlation to the Urbach energy, but the more significant parameter E a seems to depend only on the deposition-induced microstructure and not on the Urbach energy, the hydrogen content, or the hydrogen diffusion coefficient.