Review of polymorphous Ga₂O₃materials and their solar-blind photodetector applications

Abstract

Light detection in the deep-ultraviolet (DUV) solar-blind waveband has attracted interest due to its critical applications, especially in safety and space detection. A DUV photodetector based on wide-bandgap semiconductors provides a subversive scheme to simplify the currently mature DUV detection system. As an ultra-wide-bandgap (4.4–5.3 eV) semiconductor directly corresponding to the DUV solar-blind waveband, Ga2O3 has an important strategic position in the prospective layout of semiconductor technology owing to its intrinsic characteristics of high breakdown electric field, excellent tolerance of high/low temperature, high resistance to radiation, and rich material systems. As the only native substrate that can be fabricated from melt-grown bulk single crystals, β-Ga2O3 has attracted a lot of attention both in power-electronic and photo-electronic devices. In addition, other metastable phases (e.g. α, ϵ, γ) of Ga2O3 have attracted great interest due to their unique properties. In this work, we discuss the advances in achieving bulk and film Ga2O3 materials with different crystal phases. In addition, the latest achievements with polymorphous Ga2O3-based solar-blind photodetectors (SBPDs) and the methods to enhance their performance, including doping, annealing, and transparent electrodes, are also discussed. Furthermore, as the most desirable application, DUV imaging technologies based on Ga2O3 SBPDs are systematically summarized. Finally, conclusions regarding recent advances in Ga2O3 SBPDs, remaining challenges, and prospects are presented and discussed.

Deep-Level Traps Responsible for Persistent Photocurrent in Pulsed-Laser-Deposited β-Ga2O3 Thin Films

“…Ga 2 O 3 has received huge attention from the scientific community owing to its material properties such as an ultra-wide bandgap, an extremely high Baliga's figure of merit, and a large breakdown field [1][2][3][4][5]. The crystallization of Ga 2 O 3 material has been reported in α, β, γ, ε, δ, and κ phases [6,7]. Among them, the β-phase of Ga 2 O 3 has shown superiority due to the availability of melt-growth single crystals, and stability against radiation and thermal and chemical environments [8][9][10][11][12][13][14][15].…”

Balancing the Transmittance and Carrier‐Collection Ability of Ag Nanowire Networks for High‐Performance Self‐Powered Ga2O3 Schottky Photodiode

“…[ 1 ] Solar‐blind photodetectors (SBPDs) are forecast to have potential applications in many significant fields, e.g., flame detection, environmental monitoring, nonline‐of‐sight optical communication, deep‐space exploration, etc. [ 1–4 ] At present, commercial SBPDs are dominated by photomultiplier tubes and Si‐based photodiode. [ 4 ] Nevertheless, the bulky structure, fragility, and requirement of large bias voltage make photomultiplier inconvenient in outdoor applications.…”

“…[ 1–4 ] At present, commercial SBPDs are dominated by photomultiplier tubes and Si‐based photodiode. [ 4 ] Nevertheless, the bulky structure, fragility, and requirement of large bias voltage make photomultiplier inconvenient in outdoor applications. [ 5 ] And for Si‐based SBPDs, the optical filter is always necessary due to the relative narrow bandgap of 1.2 eV and the broadband response from near‐infrared to UV.…”

“…Particularly, Ga 2 O 3 , with a direct bandgap of 4.7–5.1 eV, is considered as an ideal material for solar‐blind photodetection because of its high stability, strong resistance to radiation, availability of high‐quality crystal, and suitable bandgap without the necessity of bandgap tuning. [ 2–4 ] Up to now, various high‐performance Ga 2 O 3 SBPDs with multiple structures, e.g., Schottky photodiode, [ 10 ] metal–semiconductor–metal structure, [ 11 ] heterojunction photodiode, [ 12 ] and field‐effect phototransistor, [ 13 ] have been reported. Nevertheless, a rather large bias voltage (>5 V) is needed for most of the reported Ga 2 O 3 photodetectors to obtain a satisfactory performance.…”

Transport Mechanism of Enhanced Performance in an Amorphous/Monoclinic Mixed-Phase Ga2O3 Solar-Blind Deep Ultraviolet Photodetector

“…Solar-blind deep-ultraviolet (DUV, 200~280 nm) photodetectors (PDs) with significant thermal stability and reliability have drawn considerable attention owing to the wide potential applications thereof in civil, military, and scientific research, such as high-voltage corona detection, flame detection, ozone holes monitoring, missile guidance, space communication, biochemical detection, and others [1][2][3][4][5][6]. At present, due to the relatively mature silicon technology, DUV detection is mainly dominated by silicon-based photodiodes [3], photomultiplier tubes (PMTs) [7], and charged-coupled devices (CCDs) [1,7].…”