Polycrystalline Ga₂O₃ Nanostructure-Based Thin Films for Fast-Response Solar-Blind Photodetectors

Abstract

Polycrystalline Ga2O3 nanostructure-based thin films were prepared by electron beam evaporation, followed by annealing treatment. The microstructure and optical properties of the unannealed and 800 °C annealed Ga2O3 thin films were characterized. The results showed that the 800 °C annealed Ga2O3 thin films have larger grains and shorter UV absorption wavelength in comparison with the unannealed Ga2O3 thin films. A metal/semiconductor/metal-structured photodetector based on Ga2O3 thin films was fabricated, and the UV photoresponse performances were investigated. The photodetector using an annealed Ga2O3 thin film exhibited low dark current (163 pA @ 0.25 V/μm) and high responsivity rejection ratio (R 254 nm/R 310 nm = 3.2 × 103). Significantly, under 266 nm laser pulse illumination, the annealed Ga2O3 thin-film photodetector shows fast response rise time (16.6 μs) and fall time (196.7 μs), respectively, which are faster than that of most of the reported gallium oxide solar-blind photodetectors. The fast response was attributed to the reduced defect and grain boundaries in the annealed Ga2O3 thin film. This work provides guidelines to the preparation of large-area, low-cost, and high-crystalline Ga2O3 nanostructure-based thin films and is promising to realize high-sensitivity and real-time response solar-blind photodetectors.

Photoconductive and photovoltaic metal-semiconductor-metal κ-Ga2O3 solar-blind detectors with high rejection ratios

“…The rejection ratio as a function of responsivity has been also benchmarked in figure 6(b). The developed MSM detectors in this work exhibit high rejection ratios over 10 5 , which are on the frontier of the reported Ga 2 O 3 MSM solar-blind detectors [28,30,32,[47][48][49][50][51][52][53][54][55][56]. Further improvement of material quality and structural design are undergoing.…”

“…Figure 6(a) benchmarks the responsivity (R) versus the specific detectivity (D * ) of the reported Ga 2 O 3 photodetectors with different configurations, including MSM [5,[27][28][29][30][31][32], Schottky diodes [33][34][35][36], heterostructures [22,[37][38][39][40][41] and phototransistors [42][43][44][45]. In general, the detectivity increases with the elevated responsivity and the suppressed noises, and thus, high photocurrents and low dark currents are desirable for achieving high detectivity.…”

Growth of Low-defect Si-Doped Ga2O3 Film on Fluorine-doped Tin Oxide Substrate for Self-powered and High-performance Ultraviolet Photodetector

“…Considering the structure of PDs-based Ga 2 O 3 in recent studies, the PDs with a metal–semiconductor-metal (M-S-M) structure can be fabricated with a simple process that takes advantage in practice. , Nevertheless, the PDs with MSM structures using symmetric electrodes (e.g., Au/Au and Ag/Ag at the same thickness) require a power consumption to operate. This is because generated electrons and/or holes in the semiconductor layer have no priority drift direction in the mirror symmetry of the Schottky barrier profile.…”

Single β-Ga2O3 microbelt solar-blind photodetector with high specific detectivity, high rejection ratio and fast speed

“…Nevertheless, present Ga 2 O 3 solar-blind photodetectors commonly suffered from slow response speed, large dark current, and low solar-blind/UV rejection ratio, which may be related to high sub-band-gap response, strong trapping effect, and high donor concentration caused by low crystalline quality and extensive oxygen vacancies of Ga 2 O 3 . Although homoepitaxy and high temperature oxygen annealing have been commonly used to improve the crystal quality and reduce the oxygen vacancy density, they still cannot meet the needs of high-speed, low dark current and high rejection ratio UV detection [30][31][32].…”