Investigation of single n-ZnO/i-ZnO/p-GaN-heterostructed nanorod ultraviolet photodetectors

The nanorods with the structure of n-ZnO/i-ZnO were deposited on the p-GaN layer using a vapor cooling condensation system. By using a conductive atomic force microscopy system, the rectifying diode-like behavior was observed from the single n-i-p heterostructural nanorod photodetectors. The associated dark leakage current measured from the single nanorod photodetectors operating at a reverse bias voltage of - 5 V was 4.9 pA. The photoresponsivity at 360 nm of the foregoing devices was determined to be 1481 A/W, while the efficiency-gain product measured was 5.1 × 10³. The high internal gain was attributed to the oxygen-related hole-trap states induced by the native defects and dangling bonds existed on the nanorod sidewall surface.