Self-Powered Au/MgZnO/Nanolayered Ga-Doped ZnO/In Metal–Insulator–Semiconductor UV Detector with High Internal Gain at Deep UV Light under Low Voltage

Au/MgZnO/nanolayered ZnO (Ga-doped)/In MIS (metal–insulator–semiconductor) structure UV detectors are fabricated by the PLD (pulsed laser deposition) method, and the effect of different thickness Ga-doped ZnO nanolayers on the performance of the UV detectors is studied. When thicker Ga-doped ZnO nanolayers are used in the MIS structure detectors, the device shows both a self-powered device working property and a high internal gain at deep UV light. Under 0 V bias voltage, the response of the device with a 41.3 nm Ga-doped ZnO nanolayer reaches 2.55 mA/W under 230 nm UV light; the I(254 nm)/Idark ratio of the device reached 140 under a 275 μW/cm2 UV density, which is mainly caused by the collective effect of the existing internal electric field at photogenerated carriers. Under a 5 V bias voltage, the response of the UV detector with a 53.4 nm Ga-doped ZnO layer reached 2.24 A/W under 254 nm UV light, which was mainly caused by the high internal gain from the avalanche breakdown effect. In addition, the MIS structure UV detector nearly did not respond to near UV light, so a self-powered and low voltage avalanche diode UV detector was achieved in a simple MIS device, within which the MgZnO thin film worked as both a deep UV sensitive layer and an insulated layer.