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 toward civil and military applications. Despite its superior physical properties, the high quality epitaxy of metastable phase α-Ga₂O₃ remains challenging. To this end, single crystalline α-Ga₂O₃ epilayers are achieved on nonpolar ZnO (112̅0) substrates for the first time and a high performance Au/α-Ga₂O₃/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 10³ and a detectivity of 9.66 × 10¹² 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/Ga₂O₃ and Ga₂O₃/ZnO heterointerfaces. The device also allows avalanche multiplication processes initiated by pure electron and hole injections under different illumination conditions. High avalanche gains over 10³ and a low ionization coefficient ratio of electrons and holes are yielded, leading to a total gain over 10⁵ and a high responsivity of 1.10 × 10⁴ A W^–1. Such avalanche heterostructures with ultrahigh gains and bias-tunable UV detecting functionality hold promise for developing high performance solar-blind photodetectors

Tailored Emission Properties of ZnTe/ZnTe:O/ZnO Core–Shell Nanowires Coupled with an Al Plasmonic Bowtie Antenna Array

The ability to manipulate light–matter interaction in semiconducting nanostructures is fascinating for implementing functionalities in advanced optoelectronic devices. Here, we report the tailoring of radiative emissions in a ZnTe/ZnTe:O/ZnO core–shell single nanowire coupled with a one-dimensional aluminum bowtie antenna array. The plasmonic antenna enables changes in the excitation and emission processes, leading to an obvious enhancement of near band edge emission (2.2 eV) and subgap excitonic emission (1.7 eV) bound to intermediate band states in a ZnTe/ZnTe:O/ZnO core–shell nanowire as well as surface-enhanced Raman scattering at room temperature. The increase of emission decay rate in the nanowire/antenna system, probed by time-resolved photoluminescence spectroscopy, yields an observable enhancement of quantum efficiency induced by local surface plasmon resonance. Electromagnetic simulations agree well with the experimental observations, revealing a combined effect of enhanced electric near-field intensity and the improvement of quantum efficiency in the ZnTe/ZnTe:O/ZnO nanowire/antenna system. The capability of tailoring light–matter interaction in low-efficient emitters may provide an alternative platform for designing advanced optoelectronic and sensing devices with precisely controlled response