A Review of -GaO Films: Fabrications and Photoelectric Properties.

Gallium oxide (GaO), as an ultra-wide bandgap semiconducting material, has attracted extensive research interest in recent years. Owing to its outstanding electrical and optical properties, as well as its high reliability, GaO shows great potential in power electronics, optoelectronics, memory devices, and so on. Among all the different polymorphs, -GaO is the second most thermally stable phase. It has a hexagonal crystal structure, which contributes to its isotropic physical properties and its suitable growth on low-cost commercial substrates, such as AlO, Si (111). However, there are far fewer research works on -GaO in comparison with the most thermally stable β phase. Aiming to provide a comprehensive view on the current works of -GaO and support future research, this review conducts detailed summarizations for the fabrication processes of -GaO thin films and the photoelectrical properties of -GaO-based photodetectors. The effects of different deposition parameters on film phases and qualities are discussed. The forming mechanisms of phase prepared by chemical vapor depositions (CVDs) and physical vapor depositions (PVDs) are analyzed, respectively. Conclusions are made concerning the relationships between film microstructures and properties. In addition, strategies for further improving -GaO film performance are briefly summarized.