Review of Ga2O3-based optoelectronic devices

Gallium oxide (Ga2O3), with an ultrawide-bandgap of ~4.9 eV, has attracted recently much scientific and technological attention due to its extensive future applications in power electronics (field effect transistors, Schottky barrier diodes), optoelectronics (phosphors and electroluminescent [EL] devices, solar-blind photodetectors), memory (spintronic devices, resistance random access memory devices), sensing systems (gas sensors, nuclear radiation detectors), and so on. Ga2O3 has six different polymorphs, known as α, β, γ, δ, ε, and κ. Each of these polymorphs has unique physical properties and can be widely used in various fields of devices. Among them, β-Ga2O3 has been the most widely studied and utilized due to its excellent chemical and thermal stability. Herein, we provide a review on Ga2O3-based optoelectronics, with a detailed introduction of the phosphors and EL devices and a concise summary of solar-blind photodetectors. We classify the currently reported phosphors and EL devices based on Ga2O3 undoped and doped with various elements (Eu, Er, Tm, Mn, Nd, Tb, Cr), and sort out the latest progresses of Ga2O3-based solar-blind photodetectors in various forms that include bulk single crystal, nanostructures, thin films with various device structure of metal-semiconductor-metal structure, Schottky junctions, heterojunctions, and pn junctions. Finally, conclusions and future perspectives for Ga2O3 based optoelectronic devices are presented.