Simultaneous Growth of Four GaN Crystal Sheets Using the Na-Flux Liquid-Phase Epitaxial Method: Under Different Solution Heights

The four GaN crystal sheets with an area of about 1 in. were simultaneously grown on MOCVD-GaN film seed by the Na-flux liquid-phase epitaxial (LPE) method. The effects of solution height on the growth process, thickness, morphologies, and quality of LPE-GaN crystals were researched. Two different solution heights were employed: 16 mm (abbreviated as H-16 mm) and 12 mm (abbreviated as H-12 mm). In the H-16 mm solution, the surface ridge size and growth thickness of samples #1–#3-16 mm in the top-down direction away from the gas–liquid interface show a decreasing trend, and no complete epitaxial growth is obtained for sample #4-16 mm, which indicates that there is a vertical nitrogen concentration gradient. In the H-12 mm solution, the surface morphologies of samples #1–#4-12 mm present cellular organizations of about the same size, and samples #1–#3-12 mm have approximately the same growth thickness, indicating that the vertical nitrogen concentration in the solution is relatively uniform. The FWHMs of the (0002) facet of samples #1–#3-16 mm are 598 arcsec, 174 arcsec, and 157 arcsec, respectively. Additionally, the FWHMs of the (0002) facet of samples #1–#4-12 mm are 335, 213, 224, and 220 arcsec, respectively. Therefore, by further optimizing the growth parameters, the multisheet growth method could improve growth efficiency and is feasible to achieve larger-size and higher-quality GaN single crystals in the Na-flux LPE growth method.