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Researchers successfully grew high-quality beta-gallium oxide thin films on three different crystal orientations using halide vapor phase epitaxy at temperatures up to 1150°C, achieving growth rates as high as 14.3 micrometers per hour and film thicknesses up to 42.9 micrometers. The study systematically explored how growth conditions—including temperature, pressure, and precursor flow rates—affect film quality and deposition rate, finding that all three orientations produced phase-pure crystals with excellent crystallinity. Surface morphology varied significantly with crystal orientation, with the (2̄01) surface exhibiting exceptionally smooth step-and-terrace structures with surface roughness as low as 0.17 nanometers.
Why it matters
Beta-gallium oxide is a promising wide-bandgap semiconductor for high-power electronics and ultraviolet optoelectronics. This work demonstrates a viable pathway for producing thick, high-quality gallium oxide films at industrially relevant growth rates, potentially enabling more efficient power devices and advancing the commercial viability of gallium oxide technology.
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⚠️ Preprint – Noch nicht peer-reviewed
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Abstract: In this work, we systematically investigate homoepitaxial $beta$-Ga$_2$O$_3$ growth by halide vapor phase epitaxy (HVPE) on (010), (001), and ($bar{2}$01) native substrates over a broad growth parameter space, extending the growth temperature as high as 1150 $^circ$C. The growth kinetics exhibit strong dependence on precursor supply, temperature, reactor pressure, and Ga-source-to-substrate distance. Increasing the HCl flow from 80 to 300 sccm enhances the growth rate by up to seven-fold, while increasing the temperature from 1050 to 1150 $^circ$C nearly doubles the deposition rate. At 1150 $^circ$C, atmospheric-pressure growth yields rates more than 2.5 times higher than those at 100 Torr, while reducing the O$_2$ flow to 5 sccm further increases the growth rate to 14.3 $mu$m/h, producing films up to 42.9 $mu$m thick in 3 h. Notably, phase-pure homoepitaxial layers with good crystalline quality are obtained across all three orientations, with low rocking-curve full width at half maximum (FWHM) values of 63.4, 66.6, and 42.8 arcsec for the (010), (001), and ($bar{2}$01) epilayers, respectively. The surface morphology exhibits a pronounced crystallographic dependence and evolves strongly with the HVPE growth conditions. In particular, the ($bar{2}$01) surface develops well-defined step-and-terrace morphology with local RMS roughness as low as 0.17 nm. These results extend $beta$-Ga$_2$O$_3$ HVPE homoepitaxy into a higher-temperature regime and demonstrate a broad process window for high-rate growth of thick, high-quality epilayers with strongly orientation-dependent surface evolution.