Recent advances and prospects for a GaN-based hybrid type ultraviolet photodetector

Abstract

Solid-state UV photodetectors (PD) have received numerous attention because of the advantages of small size, absence of external cooling, high selectivity, and the ability to utilize the energy band structure semiconductor materials to achieve detection across various wavelengths. III-nitride thin films, as typical wide bandgap semiconductors with mature n-type and p-type doping capabilities, are ideal candidates for solid-state UV-PDs. However, a combination between III-nitride and other wide bandgap materials can either enrich the functionality of such devices such as spectrum-selective and broadband UV detection, or offers opportunities to enhance device performance, including high photoresponsivity, high external quantum efficiency, low dark current and fast response time. This topical review focuses on giving a thorough review of the III-nitride based hybrid-type UV photodetectors, their recent progress and future prospects. This review highlights different optical and electrical properties of various materials including GaN, Ga2O3, ZnO, perovskite etc. By carefully choosing the materials on two sides of the heterojunction and modulating the thickness and fermi levels and corresponding layers, p-i-n, Schottky, or MSM type photodetectors were successfully fabricated with outstanding device performances and novel spectral-selective properties. The advantages for future development of such hybrid-type PDs will be discussed, such as inherently formed p-n junction with large depletion region at the interface of two different materials, capability of bandgap engineering to tune the band offset of conduction band and valence band, thus enabling large barrier height for one type of carrier without influencing the other. The drawbacks in hybrid-type UV-PD due to poor interface quality and challenges in forming electrical contact in nanostructure hybrid UV-PD will also be discussed.