Fabrication of a-Plane GaN Substrate Using the Sr–Na Flux Liquid Phase Epitaxy Technique

We report the fabrication of a-plane GaN single crystal substrates grown by the Na flux method. In this research, Sr was added into the flux system as additive to control the crystal habit of GaN single crystals. As the amount of Sr in the melt increased, it was found that the GaN crystal shape changed from pyramidal to prismatic crystals elongated parallel to the <0001 > direction. Additionally, liquid phase epitaxy (LPE) GaN crystals were grown in Sr–Na solution on a-plane GaN templates fabricated by metal organic chemical vapor deposition (MOCVD) on sapphire substrates. ω-scan X-ray diffraction measurements showed that the full width at half maximum (FWHM) of the (11-20) plane of the LPE GaN crystal was smaller (236 arcsec) than that of the a-plane of the GaN template (1152 arcsec).