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

We applied strain ranging from 1% compressive to ∼0.3% tensile to a-Si:H 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:H 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:H channel material, and thus reduces the effective electron mobility. We show that the mobility can be used as an indicator of local mechanical strain.