Mechanical strain-induced defect states in amorphous silicon channel layers of thin-film transistors

Abstract

In this study, we examined mechanical strain-induced defect states in hydrogenated amorphous silicon (a-Si:H) channel layers of thin-film transistors (TFTs) bent with a curvature radius of 18mm. When strain is applied to the TFTs, our devices feature strain-induced variations in threshold voltage (~1.47V), subthreshold swing (~0.36V/dec), and field-effect mobility (~0.031cm2V−1s−1). The electrical characteristics of a-Si:H TFTs on bendable substrates under mechanical strain are explained by the variation in the density of states (DOS) of defects in the channel layers. Our simulation work on the DOS in the a-Si:H channel layers under mechanical strain reveals that the mechanical strain causes not only the deformation of the density of mid-gap defect states but also an increase in the band-tail states within the band gap.