Photoresponsivity Enhancement of AlGaN/GaN Heterojunction Phototransistor with ZnO Nanodot Coating Layer

The effects of a ZnO nanodot coating layer on the photoresponsivity characteristics of an AlGaN/GaN heterojunction phototransistor was investigated. The ZnO nanodot layer was introduced on the detection surface of the phototransistor using a simple spin-coating process. The ZnO nanodot layer not only reduced the dark current but also significantly increased the photoresponsivity. At the wavelength of 300 nm, the photoresponsivity increased from 1.02 × 10⁶ to 1.76 × 10⁶ A/W.