Solar-Blind Photodetector with High Avalanche Gains and Bias-Tunable Detecting Functionality Based on Metastable Phase α-Ga 2 O 3 /ZnO Isotype Heterostructures

作者：Xuanhu Chen, Yang Xu, Dong Zhou, Sen Yang, Fangfang Ren, Hai Lu, Kun Tang, Shulin Gu, Rong Zhang, Youdou Zheng, Jiandong Ye · 发表于：ACS Applied Materials & Interfaces · 年份：2017 · DOI：10.1021/acsami.7b09812 · 被引用次数：229 · 研究领域：Ga2O3 and related materials、ZnO doping and properties、Advanced Photocatalysis Techniques

The metastable α-phase Ga 2 O 3 is an emerging material for developing solar-blind photodetectors and power electronic devices toward civil and military applications. Despite its superior physical properties, the high quality epitaxy of metastable phase α-Ga 2 O 3 remains challenging. To this end, single crystalline α-Ga 2 O 3 epilayers are achieved on nonpolar ZnO (112̅0) substrates for the first time and a high performance Au/α-Ga 2 O 3 /ZnO isotype heterostructure-based Schottky barrier avalanche diode is demonstrated. The device exhibits self-powered functions with a dark current lower than 1 pA, a UV/visible rejection ratio of 10 3 and a detectivity of 9.66 × 10 12 cm Hz 1/2 W –1 . Dual responsivity bands with cutoff wavelengths at 255 and 375 nm are observed with their peak responsivities of 0.50 and 0.071 A W –1 at −5 V, respectively. High photoconductive gain at low bias is governed by a barrier lowing effect at the Au/Ga 2 O 3 and Ga 2 O 3 /ZnO heterointerfaces. The device also allows avalanche multiplication processes initiated by pure electron and hole injections under different illumination conditions. High avalanche gains over 10 3 and a low ionization coefficient ratio of electrons and holes are yielded, leading to a total gain over 10 5 and a high responsivity of 1.10 × 10 4 A W –1 . Such avalanche heterostructures with ultrahigh gains and bias-tunable UV detecting functionality hold promise for developing high performance solar-blind photodetectors.