FORMATION AND CHARACTERIZATION OF GaN SINGLE CRYSTALS GROWN IN A Na FLUX

摘要

A melt of Na and Ga with various Ga contents was placed in a BN crucible and reacted at 650°- 750℃for 200 - 300 h with N_2 generated from the decomposition of NaN_3 in a sealed stainless-steel tube. At about 0.5 Na molar fraction (r_(Na)= Na/(Na+Ga)), GaN precipitated at the interface of the melt and gas phases, and on the wall and bottom of the crucible. Platelet single crystals with a maximum size of 2 mm grew at the inside of the interface layer. The crystals were n-type semiconductor with the electron concentration of about 10~(20)cm~(-3) and mobility of about 100 cm~2V~(-1)S~(-1) at 300 K. The near-band edge emission of GaN was observed at 360 nm by cathodoluminescence spectroscopy.