超宽禁带半导体β-Ga_2O_3及深紫外透明电极、日盲探测器的研究进展

β-Ga_2O_3是一种新型的超宽禁带氧化物半导体,禁带宽度约为4.9 eV,对应日盲区,对波长大于253 nm的深紫外一可见光具有高的透过率,是天然的日盲紫外探测及深紫外透明电极材料.本文介绍了Ga_20_3材料的晶体结构、基本物性与器件应用,并综述了β-Ga_2O_3在深紫外透明导电电极和日盲紫外探测器中的最新研究进展.Sn掺杂的Ga_2O_3薄膜电导率可达到32.3 S/cm,透过率大于88%,但离商业化的透明导电电极还存在较大差距.在日盲紫外探测器应用方面,基于异质结结构的器件展现出更高的光响应度和更快的响应速度,ZnO/Ga_2O_3核/壳微米线的探测器综合性能最佳,在-6 V偏压下其对254 nm深紫外光的光响应度达1.3×10~3A/W,响应时间为20μs.

Ultra-wide bandgap semiconductor of β-Ga2O3 and its research progress of deep ultraviolet transparent electrode and solar-blind photodetector

Gallium oxide (Ga₂O₃), with a bandgap of about 4.9 eV, is a new type of ultra-wide bandgap semiconductor material. The Ga₂O₃ can crystallize into five different phases, i.e. α, β, γ, δ, and ε-phase. Among them, the monoclinic β-Ga₂O₃ (space group:C2/m) with the lattice parameters of a=12.23 Å, b=3.04 Å, c=5.80 Å, and β=103.7° has been recognized as the most stable phase. The β-Ga₂O₃ can be grown in bulk form from edge-defined film-fed growth with a low-cost method. With a high theoretical breakdown electrical field (8 MV/cm) and large Baliga's figure of merit, the β-Ga₂O₃ is a potential candidate material for next-generation high-power electronics (including diode and field effect transistor) and extreme environment electronicshigh temperature, high radiation, and high voltage (low power) switching]. Due to a high transmittance to the deep ultraviolet-visible light with a wavelength longer than 253 nm, the β-Ga₂O₃ is a natural material for solar-blind ultraviolet detection and deep-ultraviolet transparent conductive electrode. In this paper, the crystal structure, physical properties and device applications of Ga₂O₃ material are introduced. And the latest research progress of β-Ga₂O₃ in deep ultraviolet transparent conductive electrode and solar-blind ultraviolet photodetector are reviewed. Although Sn doped Ga₂O₃ thin film has a conductivity of up to 32.3 S/cm and a transmittance greater than 88%, there is still a long way to go for commercial transparent conductive electrode. At the same time, the development history of β-Ga₂O₃ solar-blind ultraviolet photodetectors based on material type (nanometer, single crystal and thin film) is described in chronological order. The photodetector based on quasi-two-dimensional β-Ga₂O₃ flakes shows the highest responsivity (1.8×10⁵ A/W). The photodetector based on ZnO/Ga₂O₃ core/shell micron-wire has a best comprehensive performance, which exhibits a responsivity of 1.3×10³ A/W and a response time ranging from 20 \${\text{μ}}{\rm{s}}$\ to 254 nm light at -6 V. We look forward to applying the β-Ga₂O₃ based solar-blind ultraviolet photodetectors to military (such as:missile early warning and tracking, ultraviolet communication, harbor fog navigation, and so on) and civilian fields (such as ozone hole monitoring, disinfection and sterilization ultraviolet intensity monitoring, high voltage corona detection, forest fire ultraviolet monitoring, and so on).