Recent Progress in Solar‐Blind Deep‐Ultraviolet Photodetectors Based on Inorganic Ultrawide Bandgap Semiconductors

Due to its significant applications in many relevant fields, light detection in the solar‐blind deep‐ultraviolet (DUV) wavelength region is a subject of great interest for both scientific and industrial communities. The rapid advances in preparing high‐quality ultrawide‐bandgap (UWBG) semiconductors have enabled the realization of various high‐performance DUV photodetectors (DUVPDs) with different geometries, which provide an avenue for circumventing numerous disadvantages in traditional DUV detectors. This article presents a comprehensive review of the applications of inorganic UWBG semiconductors for solar‐blind DUV light detection in the past several decades. Different kinds of DUVPDs, which are based on varied UWBG semiconductors including Ga₂O₃, Mg_xZn_1?xO, III‐nitride compounds (Al_xGa_1?xN/AlN and BN), diamond, etc., and operate on different working principles, are introduced and discussed systematically. Some emerging techniques to optimize device performance are addressed as well. Finally, the existing techniques are summarized and future challenges are proposed in order to shed light on development in this critical research field.     

Ultrahigh EQE (15%) Solar‐Blind UV Photovoltaic Detector with Organic–Inorganic Heterojunction via Dual Built‐In Fields Enhanced Photogenerated Carrier Separation Efficiency Mechanism

A new strategy of constructing an additional heterojunction on the surface of epitaxially grown Ga₂O₃ film with a distorted lattice is proposed to solve the problem of low external quantum efficiency (EQE) in traditional Ga₂O₃ heterojunction photovoltaic devices. Experimentally, an organic–inorganic hybrid poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate/Ga₂O₃/p‐type Si solar‐blind ultraviolet (SBUV) photovoltaic detector is constructed to achieve an ultrahigh EQE of ≈15% at 0 V bias, which is 1–2 orders of magnitude higher than that of the Ga₂O₃ photovoltaic devices reported previously. Here, an enhanced mechanism of photogenerated carrier separation efficiency induced by dual built‐in fields is proposed to explain the high EQE of Ga₂O₃ SBUV photovoltaic devices. In addition, the organic–inorganic hybrid detector displays a high SBUV–visible rejection ratio (R_{255 nm}/R_{405 nm} of ≈450) and fast response speed (rise time of 60 ms and decay time of 88 ms). All these results indicate that the strategy proposed could provide reference for the fabrication of high‐performance Ga₂O₃ SBUV photovoltaic detectors.