The preparation and characterisation of gallium nitride using the Hi-Prexx facility

Several previously reported methods have been investigated for the production of bulk, high quality, gallium nitride powder. Two principal attempts are reported, using solid state metathesis reactions and high temperature flowing ammonia techniques. Using the latter method high purity, single-phase bulk, wurtzite gallium nitride powder was produced using a very simple method. Using the on-line Hi-Prexx facility the powders have been examined up to pressures of 41 GPa using EXAFS, X-ray diffraction and photoluminescence along with further SEM analysis. X-ray diffraction showed the powder to be highly pure P6₃mc (186) wurtzite GaN. PL studies found that there is an approximate shift with pressure of 30-37 meV/GPa and with Ga k-edge EXAFS data display a clear pressure dependency of the local structure of nearest neighbour atoms.