Tauc-plot scale and extrapolation effect on bandgap estimation from UV–vis–NIR data – A case study of β-Ga2O3

Review of polymorphous Ga2O3 materials and their solar-blind photodetector applications

Literatures reports that intrinsic Ga2O3 shows negligible response to UV wavelength longer than its optical absorption edge. Herein, we demonstrate for the first time the enhanced response of Ga2O3 to UV light with wavelength significantly longer than its optical absorption edge ≤ 280 nm. The responsivity of the photodetector reached 38.161 A/W and detectivity of 8.3916 × 10 9 Jones when the bias voltage was increased to 3 V for 365 nm light illumination. X-ray diffraction measurement confirmed mixed-phase β- α Ga2O3 with high crystallinity. Microstructural observation revealed nanoplates-like morphology, showing the high crystallization of the nanocrystals. Optical reflectance measurement showed optical bandgap of 4.67 eV which is typical of β-Ga2O3. The sensitivity of the wide bandgap semiconductor material to wavelength longer than its absorption edge could be ascribed to the high crystallinity, film density and net oxygen vacancies on the film.

Development and characterization of MSM UV photodetector based on gallium oxide nanostructures

$\beta $ -Ga2O3 is one of the promising semiconductor materials that has been widely used in power electronics and ultraviolet (UV) detectors due to its wide bandgap and high sensitivity to UV light. Specifically, for the UV detection application, it has been reported that the photocurrent was in the scale of microamps ( $\mu \text{A}$ ), which normally requires sophisticated signal processing units. In this work, a novel approach based upon coupling of two Schottky diodes is reported, leads to a substantial increase in photocurrent (~186 times) when benchmarked against a conventional planar UV photodiode. The detectivity and responsivity of the new device have also been significantly increased; the rectification ratio of this device was measured to be $1.7\times 10^{7}$ with ultralow dark current, when measured in the reverse bias. The results confirm that the approach of coupling two Schottky diodes has enormous potential for improving the optical performance of deep UV sensors.

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P J Cao

Papers

Preparation of Ga 2 O 3 thin film solar-blind photodetectors based on mixed-phase structure by pulsed laser deposition