Device Characterization of p/i/n Thin-Film Phototransistor for Photosensor Applications

A promising photodevice, called p/i/n thin-film phototransistor, has been characterized from the viewpoint of operation condition and device behavior. It is found that the detected current becomes maximal when the control voltage is equal to the applied voltage. This is because a depletion layer is widely formed, and generated carriers are transported through an electron channel with high conductance instead of a hole channel. Finally, we propose a diode-connected structure as a sensitive photodevice.