Na flux growth and characterization of GaN single crystals

Bulk GaN single crystals with a size of 1-2 mm were prepared using Na flux at 600-800 °C. Morphology of the crystals were platelet or prismatic. Polarity of the crystals was determined by x-ray single crystal analysis using X-ray anomalous dispersion. Hall measurement was carried out for orange color platelet crystals. The crystals were n-type semiconductor with the electron concentration of about 10²⁰ cm^-3 and mobility of 10-100 cm²v^-2s^-1 at room temperature. The near-edge emission of GaN was observed at 363 nm in the cathodoluminescence spectra of the colorless prismatic single crystals.