Exciton photo-luminescence of GaN bulk crystals grown by the AMMONO method

GaN in form of microcrystals were obtained using a new technique—the AMMONO method. The growth was performed at relatively low temperature and pressure conditions, in comparison with other techniques used for GaN growth. The AMMONO crystals were of pure hexagonal phase and had a low electron concentration of about 5×1015 cm−3. Their luminescence was very intensive and homogenous. At helium temperatures exciton recombinations of record narrow lines (FWHM down to 1 meV) dominated the luminescence spectra. Energy positions of the exciton lines did not depend on excited microcrystals which confirmed they were strain-free.