Morphology and characterization of GaN single crystals grown in a Na flux

Abstract

Morphology of GaN single crystals grown in a Na flux at 750°C for 100 h was observed by scanning electron microscopy. It changed from prismatic to platelet and fine grains with increasing rNa=Na/(Na+Ga) molar ratio of starting materials. Hall measurement was carried out for GaN single crystals with a size of 0.4–0.7 mm. The electron concentration and mobility were about 1020 cm−3 and 10–100 cm2 V−1 s−1 at room temperature. The near band-edge emission of GaN was observed at 363 nm by cathodoluminescence spectroscopy.