Status and Outlook of Metal–Inorganic Semiconductor–Metal Photodetectors

Metal–inorganic semiconductor–metal photodetectors (MSM-PDs) have received great attention in many areas, such as optical fiber communication, sensing, missile guidance, etc., due to their inherent merits of high speed, high sensitivity, and easy integration. This review focuses on MSM-PDs with the semiconductor layer made of inorganic materials including traditional semiconductors (such as GaAs and Si), the third-generation wide bandgap semiconductors (such as GaN, ZnO, and SiC), as well as several emerging semiconductors (such as perovskites and 2D materials). First, the basic structures of MSM-PDs, including the planar and vertical configurations, are presented. Then, their working principles of MSM-PDs are discussed. Subsequently, the research progresses on MSM-PDs consisting of different photosensitive semiconductor materials are described in detail. Additionally, the efforts to optimize MSM-PDs from the aspects of dark current, response speed, responsivity, spectral adjustment, etc., are also introduced. Finally, the review is concluded with the perspectives of MSM-PDs from the authors’ vision.