Self‐Powered and Spectrally Distinctive Nanoporous Ga<sub>2</sub>O<sub>3</sub>/GaN Epitaxial Heterojunction UV Photodetectors
Tiwei Chen, Xiaodong Zhang, Yongjian Ma, Tao He, Xing Wei, Wenbo Tang, Wenxin Tang, Xin Zhou, Houqiang Fu, Li Zhang, Kun Xu, Chunhong Zeng, Yaming Fan, Yong Cai, Baoshun Zhang
Abstract
Herein, self‐powered spectrally distinctive UV photodetectors (PDs) based on nanoporous epitaxial Ga 2 O 3 /GaN heterojunctions grown by metalorganic chemical vapor deposition (MOCVD) are reported. The nanoporous structures are formed by a novel self‐reactive etching (SRE) method, which significantly enhances the device performance. PDs with different porosities are fabricated and compared. In the self‐powered mode, the PD with the highest nanopore porosity exhibits the best performance, with an ultralow dark current of 0.04 nA, a fast photoresponse speed, and a high responsivity of 43.9 mA W −1 (35.8 mA W −1 ) under 254 nm (365 nm) illumination, which is 800% higher than that of the reference device without the porous structure. Furthermore, opposite current polarities are observed in the PDs under different illumination spectra, the mechanism of which is explained by the carrier transportation using the device band diagrams. This phenomenon can be used to distinguish different incident spectra, opening the door to more new applications. This work represents one of the first spectrally distinctive self‐powered UV PDs based on nanoporous Ga 2 O 3 /GaN heterojunctions and significantly benefits the development of multifunctional UV PDs.