MOVPE growth of nonpolar a-plane GaN with low oxygen contamination and specular surface on a freestanding GaN substrate

We investigated unintentionally doped nonpolar a- and m-plane GaN layers grown by metalorganic vapor phase epitaxy under several sets of conditions on freestanding a- and m-plane GaN substrates. Oxygen contamination in a-plane GaN is greatly reduced by increasing the V/III ratio during growth. As a result, a high-resistivity GaN buffer layer for an AlGaN/GaN heterostructure field-effect transistor was realized.

► We investigated the growth of non-polar a-plane and m-plane GaN. ► Control of the V/III ratio is effective for reducing contamination in GaN. ► Control of the growth temperature is effective for reducing contamination in GaN. ► We realized high-quality nonpolar a-plane AlGaN/GaN wafer. ► The results of this study can be applied to nonpolar a-plane HFETs.