Beta-(AlxGa1−x)2O3 thin films were prepared on c-plane sapphire substrates by low-pressure reactive vapor deposition at different temperature. The crystal structure, surface morphology, and optical properties of β-(AlxGa1−x)2O3 films were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), and transmission spectra. The β-(AlxGa1−x)2O3 films were preferred [ 2 ¯ 01] orientation. The film grown at 1400 °C has narrower full width half maximum (FWHM) than grown at 1450 °C. As the growth temperature increases, the Al group decreases. The Al content of β-(AlxGa1−x)2O3 films grown at 1400 °C and 1450 °C are x = 0.524 and x = 0.489, respectively. The SEM and AFM images showed different growth mode for β-(AlxGa1−x)2O3 films grown at 1400 °C and 1450 °C and their root-mean-square roughness (RMS) values are 5.27 nm and 5.33 nm, respectively. All the prepared β-(AlxGa1−x)2O3 films have high transmittances exceeding 90% in visible region and large optical bandgap above 6 eV. These results indicate that low-pressure reactive vapor deposition technology is a promising growth technology for a high quality β-(AlGa)2O3 films with tunable properties.

AbstractThe possibility of scanning electron microscope (SEM) observation and energy dispersive X-ray (EDX) spectrometry analysis in microscale regions of insulating samples using diluted ionic liquid was investigated. It is possible to obtain clear secondary electron images of insulating samples such as a rock and mineral at 5,000 times magnification by dropping 10 μL of 1 wt% of 1-ethyl-3-methylimidazolium acetate (EMI-CH3COO) diluted with ethanol onto the samples. We also obtained EDX spectra of the samples in microscale regions (∼5 μm2) without overlapping EDX spectra of other minerals with different composition. It might be possible to perform quantitative analysis of the samples if a method that does not need standard samples is applied or an X-ray detector sensitive for light elements was attached. The method of dropping 1 wt% EMI-CH3COO diluted with ethanol onto insulating samples is useful for SEM observation, EDX analysis in microscale regions, and the preservation of scarce rock and mineral samples because ionic liquid can be easily removed with acetone.

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