Temperature dependence of photocurrent in an amorphous GaInZnO/InZnO thin film transistor

The temperature dependence of the photocurrent of amorphous GaInZnO/InZnO thin film transistors was investigated at various illumination wavelengths. The photocurrent is highly dependent on the irradiation conditions, even though the saturation characteristics were similar regardless of illumination. When the photon energy was greater than 2.82 eV, it was large enough to excite a bound electron independent of the thermal energy. When the irradiation photon energy was not large enough for direct excitation, it was observed that the states in the Urbach tail region, approximately 0.18-0.28 eV below the conduction band, acted as shallow traps that induced a thermally activated photocurrent.