Enhanced Light–Matter Interaction and Efficient Energy Transfer in Ga ₂ O ₃ Photodetectors Based on van der Waals Heterogeneous Structures

New generation wide bandgap semiconductor gallium oxide (Ga 2 O 3 ), with a decent optical bandgap and absorbance cutoff wavelength, has been a desired material for constructing deep-ultraviolet photodetectors, highlighting advantages of low noise and high sensitivity. Considering two key matters, “light–matter interaction” and “light absorbance”, influencing the photodetection performance, additional materials are required to fabricate heterostructures with Ga 2 O 3 to overcome the intrinsic limitations of a single material. A compensatory material should be chosen to develop heterointerfaces with Ga 2 O 3 to collect excitons, concerning the photon excitation and carrier transport. This scheme would solve the conflict between strong light absorbance and weak light–matter interaction. The emerging van der Waals (vdW) system features free stacking, no surface-free bonding, and easy control of dark current by an external field, providing a new opportunity to study heterogeneous deep-ultraviolet optoelectronics, catering to the demand for developments in modern optics, materials science, physics, electronics, etc. Progress in materials preparation contributes to the convenience of fabrication of vdW heterojunctions to discover abundant novel properties in optoelectronic devices, which are desired in various scientific fields. Although the vdW heterojunction displays huge potential, it is yet to achieve practical application. Therefore, in this review article, its advantages and inherent mechanisms are discussed and analyzed in view of enhanced light–matter interaction and efficient energy transfer across heterointerfaces, in order to give insights into the interfaces of Ga 2 O 3 -based vdW heterostructures.