Zinc-Blende-Type Cubic GaN Single Crystals Prepared in a Potassium Flux

Single crystals of zinc-blende-type cubic GaN (c-GaN, space group F43m, lattice parameter a=4.5062(9) Å) were synthesized at 750°C by the reaction of Ga and N2 in a potassium flux. The crystal structure was analyzed by single-crystal X-ray diffraction with an R1-factor of 2.1% (R1=Σ∥F o-F c∥/Σ|F o|), where F o is the observed structure factor and F c is the calculated structure factor). A peak of near-band-edge emission was observed at 3.20 eV in the cathodoluminescence spectrum measured at 25°C.