1 research outputs found
Solar-Blind Photodetector with High Avalanche Gains and Bias-Tunable Detecting Functionality Based on Metastable Phase α‑Ga<sub>2</sub>O<sub>3</sub>/ZnO Isotype Heterostructures
The
metastable α-phase Ga<sub>2</sub>O<sub>3</sub> 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<sub>2</sub>O<sub>3</sub> remains challenging. To this end,
single crystalline α-Ga<sub>2</sub>O<sub>3</sub> epilayers are
achieved on nonpolar ZnO (112Ì…0) substrates for the first time
and a high performance Au/α-Ga<sub>2</sub>O<sub>3</sub>/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<sup>3</sup> and a detectivity of 9.66 × 10<sup>12</sup> cm Hz<sup>1/2</sup> W<sup>–1</sup>. 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<sup>–1</sup> at −5 V, respectively. High
photoconductive gain at low bias is governed by a barrier lowing effect
at the Au/Ga<sub>2</sub>O<sub>3</sub> and Ga<sub>2</sub>O<sub>3</sub>/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<sup>3</sup> and
a low ionization coefficient ratio of electrons and holes are yielded,
leading to a total gain over 10<sup>5</sup> and a high responsivity
of 1.10 × 10<sup>4</sup> A W<sup>–1</sup>. Such avalanche
heterostructures with ultrahigh gains and bias-tunable UV detecting
functionality hold promise for developing high performance solar-blind
photodetectors