Photo sensitivity of p-type low-temperature polycrystalline silicon thin-film transistors by adjusting the channel doping dosage

This paper reports the effects of different light intensity of white color LEDs illuminated on P-TFT devices doped and un-doped with B₂H₆ inside the polycrystalline silicon channel with different channel width/length (W/L) by analyzing I_d-V_g transfer curves. Results indicate that the threshold voltage (V_th), of the p-TFT device was shifted to positive values by increasing illumination intensity, and C-V curves will be in accordance with the V_th shift to positive voltage. Off Current (I_off) and sub-threshold swing (S.S.) of p-TFT devices were increased with increasing illumination intensity. The reason why the doped p-TFT devices revealed much photo sensitivity is correlated with B₂H₆ dosage doping directly inside the grain boundaries of the p-channel creating the deep traps and inside the gate dielectric creating the electron traps, and causes larger V_th shift and worse device degradation from second ion magnet spectroscopy (SIMS) analysis.