Solar-Blind Photodetector with High Avalanche Gains and Bias-Tunable Detecting Functionality Based on Metastable Phase α-Ga2O3/ZnO Isotype Heterostructures

The metastable α phase Ga2O3 is an emerging material for developing solar-blind photodetectors and power electronic devices towards civil and military applications. Despite of its superior physical properties, high quality epitaxy of metastable phase α-Ga2O3 remains challenging. To this end, single crystalline α-Ga2O3 epilayers are achieved on nonpolar ZnO (11-20) substrates for the first time and a high performance Au/α-Ga2O3/ZnO isotype heterostructures 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 7.83×10^13 cm Hz1/2/W. Dual responsivity bands with cutoff wavelengths at 255 nm and 375 nm are observed with their peak responsivities of 0.5 and 0.071A/W at -5V, respectively. High photoconductive gains at low bias is governed by barrier lowing effect at Au/Ga2O3 and Ga2O3/ZnO hetero-interfaces. The device also allows avalanche multiplication processes initiated...