Effects of mechanical strain on amorphous silicon thin-film transistor electrical stability

Abstract

The electrical stability of hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) on flexible substrates was characterized under mechanical bending. TFT lifetime until 50% reduction in IDS under moderate constant-voltage gate bias (<2 MV/cm gate field for 104 s) was estimated to be 2.56 h and 7.43 h under uniaxial applied compression and tension, respectively, compared to 4.28 h without strain. The stretched-exponential model for VT shift in a-Si:H TFTs was fitted to measurement data and used to predict how applied strain can affect TFT lifetime in practical applications. VT relaxation showed a logarithmic time dependence as would be expected for dielectric/interface charge detrapping.