The ultra-wide energy bandgap (4.6-4.9 eV) of the β-Ga2O3 semiconductor offers intrinsic solar blindness, which is a great advantage as the absorber material of a deep ultraviolet (UV) photodetector. Although the band-to-band excitation transition in β-Ga2O3 is allowed solely by the UV-C wavelength, the defective sites including oxygen vacancies can induce sub-bandgap absorption, resulting in high background noise. The UV-ozone treatment was performed at elevated temperatures to investigate its effect on removing these oxygen vacancies; it creates reactive oxygen radicals that can reach the β-Ga2O3 lattice and passivate the defective sites. The chemical analysis through x-ray photoelectron and micro-Raman spectroscopies revealed an increase in Ga-O bonding after UV-ozone treatment. The optoelectrical measurements on the β-Ga2O3 UV-C photodetectors showed that the UV-ozone treatment significantly decreased the response to UV-A light. Thus, the photodetector performance (photo-to-dark current ratio, responsivity, detectivity, and rejection ratio) was greatly enhanced; especially, the rejection ratio was increased to 4.56 × 108 by eight orders of magnitude after UV-ozone treatment. The remarkably improved UV-C selectivity in the β-Ga2O3 solar-blind photodetector highlights its potential of realizing truly solar-blind photodetectors using a simple UV-ozone treatment technique.
Bibliographical noteFunding Information:
This research was supported by the Institute of Civil Military Technology Cooperation funded by the Defense Acquisition Program Administration and Ministry of Trade, Industry and Energy of Korean government and National R&D Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (2020M3H4A3081799).
© 2020 Author(s).
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)