Journal
APPLIED PHYSICS LETTERS
Volume 117, Issue 26, Pages -Publisher
AIP Publishing
DOI: 10.1063/5.0030400
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Funding
- Institute of Civil Military Technology Cooperation - Defense Acquisition Program Administration
- Ministry of Trade, Industry and Energy of Korean government
- National R&D Program through the National Research Foundation of Korea (NRF) - Ministry of Science and ICT [2020M3H4A3081799]
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The ultra-wide energy bandgap (4.6-4.9eV) of the beta-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 beta-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 beta-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 beta-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 4.56x10(8) by eight orders of magnitude after UV-ozone treatment. The remarkably improved UV-C selectivity in the beta-Ga2O3 solar-blind photodetector highlights its potential of realizing truly solar-blind photodetectors using a simple UV-ozone treatment technique.
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