Simulation and Modelling of a Vertical a-Si:H PIN Photodiode-Gated LTPS TFT

To enable low-dose dynamic X-ray imaging, a novel active pixel sensor (APS) with a dual-gate low-temperature polycrystalline silicon thin-film transistor (LTPS TFT) as a readout TFT vertically gated by an amorphous silicon p-i-n photodiode is modeled and simulated in this paper. The result from TCAD simulation shows that the subthreshold swing (SS) of this hybrid integrated sensor is 0.18 V/decade and the top gate-threshold voltage dependence parameter γ is -1.04. Small SS, Jstrong photo-induced top gate dependence and high fill factor make it promising for a flat-panel X-ray detector with fast response and high sensitivity.