High Responsivity β-Ga₂O₃ Metal–Semiconductor–Metal Solar-Blind Photodetectors with Ultraviolet Transparent Graphene Electrodes

Abstract

We demonstrated high responsivity metal–semiconductor–metal (MSM) solar-blind photodetectors by integrating exfoliated β-Ga2O3 microlayers with graphene, which is a deep ultraviolet (UV) transparent and conductive electrode. Photodetectors with MSM structures commonly suffer from low responsivity, although they feature a facile fabrication process, low dark current, and fast response speed. The β-Ga2O3 MSM solar-blind photodetectors with graphene electrodes exhibited excellent operating characteristics including higher responsivity (∼29.8 A/W), photo-to-dark current ratio (∼1 × 106%), rejection ratio (R 254nm/R 365nm, ∼9.4 × 103), detectivity (∼1 × 1012 Jones), and operating speed to UV-C wavelengths, compared with MSM photodetectors with conventional metal electrodes. Absence of shading by the integration of graphene with β-Ga2O3 allows maximum exposure to the incident photons, suggesting a great potential for deep UV optoelectronic applications.

Catalyst‐Free Vapor–Solid Deposition Growth of β‐Ga2O3 Nanowires for DUV Photodetector and Image Sensor Application

“…According to the above equations, the NEP was calculated to be ≈1.73 × 10 −16 W Hz −1/2 , which led to a D * value of ≈8.16 × 10 12 Jones. Such a high D * value is comparable with the values of a single‐crystalline Sn‐doped β‐Ga 2 O 3 wafer/graphene heterojunction DUV photodetector (≈10 13 Jones) and a exfoliated single‐crystalline β‐Ga 2 O 3 microflake MSM DUV photodetector with graphene electrodes (≈1.45 × 10 12 Jones) …”

“…To date, a number of DUV photodetectors based on β‐Ga 2 O 3 in the form of either thin films or nanostructures have been successfully developed . Benefiting from quantum confinement effect and remarkable surface/size effect, β‐Ga 2 O 3 nanostructures, in particular 1D β‐Ga 2 O 3 nanowires (NWs) or nanobelts (NBs), can exhibit attractive merits of better optical absorption, improved charge carrier transportation, and increased surface states to interact with surroundings, over their thin films' counterpart .…”

High-temperature photocurrent mechanism of β-Ga2O3 based metal-semiconductor-metal solar-blind photodetectors

“…It was observed that the photocurrent was varied lesser than the dark current with temperature increment. Photocurrent to dark current (PDCR) ratio is also an essential parameter of photodetectors which was calculated using the following equation: [36][37]…”

Demonstration of zero bias responsivity in MBE grown β-Ga2O3 lateral deep-UV photodetector

“…Excellent solar-blind performance with high responsivity and low dark currents have been reported for β-Ga 2 O 3 deep-UV photodetectors. 6,[26][27][28][29][30][31][32] Both Schottky 14,17,27,30,[32][33][34] and metal-semiconductor-metal (MSM) 7,9,13,[19][20][21]35,36) type device architecture have been studied on bulk as well as epitaxial β-Ga 2 O 3 on foreign substrates. Battery-free, self-powered UV detectors reduce the weight and power supply requirement of imagers and prove to be beneficial in terms of reducing the footprint and complexity of systems.…”

“…(4), the averaged value of D + considering the contributions from thermal noise and noise due to dark current was estimated to be 2.0 × 10 12 Jones at 1 V which matches with the reported values. 7,15,35) Such high detectivity value of photodetectors is suitable to enable planar focal plane arrays using readout integrated circuit (ROIC). vertical Schottky detectors respectively, yet there has been no report on zero-bias responsivity for planar and epitaxial β-Ga 2 O 3 UV photodetectors with MSM based architecture.…”