Single crystal β-Ga2O3 epitaxial layers have been prepared on c-axis (0001) sapphire substrates using metalorganic chemical vapor deposition technique at relatively low temperature. Post-annealing of β-Ga2O3 single crystals up to 800 °C does not affect the crystallinity, explored by x-ray diffraction, showing that β-Ga2O3 epitaxial layers are highly (-201) oriented. Metal-semiconductor-metal devices are fabricated on single crystals to study their photoresponsivity. A significant improvement in performance of post annealed-based devices is observed, attributed to point defect reduction. Annealing of as-grown samples results to a significant decrease in both oxygen and gallium vacancies, which are sources of current leakage.
Highly (-201) oriented β-Ga2O3 films prepared by metal-organic chemical vapor deposition on (0001) sapphire substrates, undergone different post annealing temperatures to study their resistivity under harsh environment. Both of Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy (TEM) results are exposing a harmony between oxygen vacancies and gallium interstitials. TEM characterization of samples determines a relationship between interstitials and formation of screw dislocations. Cathodoluminecsnece investigated under different applied voltages is found to be applicable to study chemistry of the bulk and surface of β-Ga2O3.
The β-Ga2O3 films were grown on (0001) sapphire at 500 °C by metal organic chemical vapor deposition. In the
analysis of crystal structure, we found that the (-201) oriented single crystal β-Ga2O3 epilayer can be obtained under low
chamber pressure of 15 torr. Moreover, a metal-semiconductor-metal solar-blind deep ultraviolet photodetector was
fabricated with the β-Ga2O3 epilayer. As the bias voltage is 5 V, the photodetector exhibits a relatively low dark current
about 0.2 pA, which induced by the highly resistive nature of the β-Ga2O3 thin films. From the responsivity result, it can
be observed that photodetector shows a maximum responsivity at 260 nm, revealing the β-Ga2O3 photodetector was
really solar-blind. The responsivity of the photodetector was as high as 20.1 A/W with an applied bias of 5 V and an
incident light wavelength of 260 nm. The improved performance is attributed to the high quality of β-Ga2O3 epilayer.