Field-effect mobility of amorphous silicon thin-film transistors under strain

We applied strain ranging from 1% compressive to similar to0.3% tensile to a-Si:M TFTs on polyimide foils by bending them inward or outward, or by stretching them in a microstrain tester. We also applied strain to a-Si:M TFTs by deforming a flat substrate into a spherical dome. In each case, compression lowered and tension raised the on-current and hence the electron field-effect mobility. We conclude that compressive strain broadens both the valence and conduction band tails of the a-Si:M channel material, and thus reduces the effective electron mobility. We show that the mobility can be used as an indicator of local mechanical strain. (C) 2004 Elsevier B.V. All rights reserved.