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

Abstract

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 Ga 2 O 3 , Mg x Zn 1−x O, III-nitride compounds (Al x Ga 1−x N/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.with energy much higher than the semiconductor bandgap. Moreover, due to light absorption by the surface passivation layers, typically Si oxide, quantum efficiency in the DUV range is greatly reduced. The passivation layers are also easily degraded by UV illumination. Finally, for highly sensitive UV photodetection, the detectors need to be cooled to reduce dark current; the cooled detectors, however, behave like cold traps for contaminants which degrade the detectivity.In the past two decades, the emergence of UV photodetectors based on wide-bandgap (WBG) semiconductors has opened up an avenue to circumvent the above-mentioned dilemma. The WBG semiconductors such as SiC, GaN, and some group II-V compounds, typically have bandgaps exceeding ≈3.10 eV, enabling room-temperature detectors to possess fast response speed, and offering intrinsic visible-blindness (response cutoff wavelength: ≈400 nm). [14][15][16] Moreover, these semiconductors generally possess significantly higher thermal conductivity than Si, which renders them suitable for operation in harsh environments (e.g., high temperature and high power). The electron velocity of these materials at large electric fields is generally higher than that of common semiconductors, although WBG semiconductors exhibit relatively lower electron and hole mobilities. Compared with the abovementioned conventional WBG semiconductors, ultrawide-bandgap (UWBG) semiconductors, as the next generation of semiconductor materials with bandgaps significantly wider than the 3.4 eV of GaN, are particularly suitable for solar-blind DUV light detection. [17][18][19][20]

Low‐dimensional nanomaterial/Si heterostructure‐based photodetectors

“…This also results in a large external quantum efficiency (EQE) and responsivity. Nevertheless, the high dark current and slow response speed of such devices severely restrict their applications in some fields, such as light communication and photoswitching …”

“…Nevertheless, the high dark current and slow response speed of such devices severely restrict their applications in some fields, such as light communication and photoswitching. 23 2.1.2 | P-n/Schottky junction photodiode P-n junction photodiodes are made up of semiconductors with opposite conductivity types. The photovoltaic effect dominates the photoresponse in p-n junction photodetectors.…”

Tunable self‐powered n‐SrTiO3 photodetectors based on varying CuS‐ZnS nanocomposite film (p‐CuZnS, p‐CuS, and n‐ZnS)

“…Photodetectors, which detect irradiation directly by transforming light into electrical signals based on photoelectric effect, have been extensively used in various applications, such as environmental monitoring, biological/chemical analysis, flame detection, and communications . Recently, many groups are dedicated to realizing photodetectors with self‐powered characteristics .…”

“…Photodetectors, which detect irradiation directly by transforming light into electrical signals based on photoelectric effect, have been extensively used in various applications, such as environmental monitoring, biological/chemical analysis, flame detection, and communications. [1][2][3][4][5][6][7] Recently, many groups are dedicated to realizing photodetectors with self-powered characteristics. [8][9][10][11][12] The self-powered devices can work under zero bias due to the photovoltaic effect from p-n junctions or heterojunctions under light illumination, and are particularly appealing for their miniaturization and portability.…”

Ultrahigh Responsivity UV Photodetector Based on Cu Nanostructure/ZnO QD Hybrid Architectures

“…Ultraviolet (UV) detection technique has developed a wide potential range of applications in both civilian and military fields, such as environmental monitoring, flame sensing, and space exploration . UV photodetectors show many excellent properties including intrinsically less interference from the visible region, high radiation hardness, and filter free . Owing to relatively high saturated carrier drift rate, large exciton energy (60 meV), and wide direct bandgap, ZnO has drawn abundant research interests as an alternative candidate for the fabrication of high‐performance UV photodetectors.…”