Suppression of persistent photoconductivity in high gain Ga<sub>2</sub>O<sub>3</sub> Schottky photodetectors*
Haitao Zhou, Lujia Cong, Jiangang Ma, Bingsheng Li, Haiyang Xu, Yichun Liu
Abstract
The defect-related photoconductivity gain and persistent photoconductivity (PPC) observed in Ga 2 O 3 Schottky photodetectors lead to a contradiction between high responsivity and fast recovery speed. In this work, a metal–semiconductor–metal (MSM) Schottky photodetector, a unidirectional Schottky photodetector, and a photoconductor were constructed on Ga 2 O 3 films. The MSM Schottky devices have high gain (> 13) and high responsivity (> 2.5 A/W) at 230–250 nm, as well as slow recovery speed caused by PPC. Interestingly, applying a positive pulse voltage to the reverse-biased Ga 2 O 3 /Au Schottky junction can effectively suppress the PPC in the photodetector, while maintaining high gain. The mechanisms of gain and PPC do not strictly follow the interface trap trapping holes or the self-trapped holes models, which is attributed to the correlation with ionized oxygen vacancies in the Schottky junction. The positive pulse voltage modulates the width of the Schottky junction to help quickly neutralize electrons and ionized oxygen vacancies. The realization of suppression PPC functions and the establishment of physical models will facilitate the realization of high responsivity and fast response Schottky devices.