Effect of UV illumination on inverted-staggered a-Si:H thin film transistors

The hydrogenated amorphous silicon thin-film transistors (a-Si:H TFT's) have been widely used as switching devices for large-area electronics, such as active matrix liquid crystal displayers. Effect of UV Illumination on improving device switching characteristics has been experimentally observed and studied. However, the inside mechanisms including state and density of traps, are not clear yet. In this work, to characterize the optimal device characteristics, we thus solve a set of Poisson, electron/hole continuity, and lattice heat flow equations coupling with density and distribution of trap states in the a-Si:H layer. The I-V characteristics of the inverted staggered a-Si:H TFT's with different magnitude of UV light illumination is for the first time calculated and carefully calibrated with experimental measured data. It is found that the traps states in the a-Si:H layer and the movement of Fermi level from the conduction band after UV illumination. This study provides an insight into the effect of UV illumination and the mechanism to improve the switching characteristics of a-Si TFTs.