Effect of Precise Control of V/III Ratio on In-Rich InGaN Epitaxial Growth

Abstract

In-polarity In0.7Ga0.3N films were grown by radio-frequency plasma-assisted molecular beam epitaxy (rf-MBE) and the dependences of crystalline quality on V/III ratio and growth temperature were investigated. To precisely control V/III ratio, In and Ga beams were periodically interrupted by closing their shutters, which is called a shutter control method in this study. With a change in V/III ratio, the crystalline quality of the In0.7Ga0.3N films markedly changed. It was found that the phase separation in the InGaN films tends to occur under metal-rich conditions but this can be prevented in N-rich and shutter-controlled growth as well. A sample grown by the shutter control method at 550 °C showed the best crystalline quality. The X-ray rocking curve full width at half maximum (FWHM) for (0002) diffraction was 287 arcsec, which is much smaller than that of a standard MBE-grown In0.7Ga0.3N film, whose FWHM is about 600 arcsec.