Synthesis of GaN Crystals by Nitrogen Pressure-Controlled Recrystallization Technique in Na Alloy Melt

Abstract

GaN crystals are synthesized by recrystallization technique in Na-Li-Ca alloy melt under different N2 pressure. X-ray powder diffraction results confirm that the structure of crystals is GaN with wurtzite type and there still have raw powders remaining. The total mass of GaN decreases with the nitrogen pressure reduces. No GaN crystals are found in the solution under N2 pressure of 0.4 MPa. The morphologies of the crystal are mainly prism and pyramid. The size of the crystal increases when closer to the liquid surface. Raman spectra indicates that these crystals are stress-free and crystal grown at 3.6 MPa has high structural quality or low impurity concentrations. The results reveal that the solubility and supersaturation of the solution are controlled by N2 pressure. The principle of GaN crystal synthesis by recrystallization is discussed.