Modifying subgap states with hydrogen incorporation from source/drain alloys for oxide phototransistors

Phototransistors with amorphous oxide semiconductors (AOSs) have attracted considerable attention owing to their low leakage current density and process compatibility with the active array. In this study, we introduce hydrogen (H) from the source/drain electrodes to the active layer using a Ti-based alloy, specifically MoTi. The device with MoTi electrodes exhibits a more negatively shifted Von value of-3.34 V compared to the device with MoAl electrodes. The H in the oxide semiconductor passivates the oxygen vacancy states and generates additional deep states above the oxygen vacancy states. Consequently, phototransistors with MoTi electrodes demonstrate a higher photoresponse under green and blue light.