Abstract
? 2022 Elsevier B.V.In this work, hetero-epitaxy of ε-Ga2O3 thin films are grown on c-plane sapphire by metal-organic chemical vapor deposition (MOCVD). Different oxygen precursors of deionized water (H2O) or high-purity nitrous oxide (N2O) gas are used and their impacts on crystal structure, optical absorption, cathodoluminescence, and photoelectric properties have been intensively studied. X-ray diffraction (XRD) analysis has shown that the ε-Ga2O3 epilayers are highly (001) oriented and the VI/III ratio is a critical growth parameter for the phase purity of Ga2O3. Cathodoluminescence (CL) measurements reveal that the luminescence peaks appear in the violet–blue–green region. A general increase of luminescence intensity is evidenced for samples grown using H2O as oxygen sources, which is explained by higher radiation recombination. Deep-ultraviolet (DUV) photodetectors with metal-semiconductor-metal (MSM) structure have been fabricated based on the ε-Ga2O3 thin films. The comparison of the device performances shows that faster response speed and higher responsivity are obtained for the device based on the ε-Ga2O3 grown by H2O as precursors, which indicates the potential of high quality ε-Ga2O3 to be applied in DUV photodetectors.
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