Electrical properties correlated with redistributed deep states in a-Si:H thin-film transistors on flexible substrates undergoing mechanical bending

The formation of trapped states due to mechanical strain dominates the characteristics of a-Si:H thin-film transistors. The behavior of electrical characteristics affected by mechanical strain can be explained by the redistribution of trap states in the bandgap. The disordered bonds may generate a redistribution of trap states, resulting in unstable electrical characteristics, such as threshold voltage, subthreshold swing, and the mobility of carriers. During a mechanical strain, the deep states are redistributed into a Gaussian distribution and are dissimilar to ordinary acceptor-like deep states, which have exponential distributions. It is concluded that the gap state density of an a-Si:H layer under the effects of mechanical strain is fundamental to the reliability and development of flexible electronics.

► The trap formation by mechanical strain dominates the characteristics.
► Weak or broken bonds may contribute to the redistribution of trap states.
► The deep states are redistributed into a Gaussian distribution.