Polariton effects in reflectance and emission spectra of homoepitaxial GaN

摘要: Reflectance and photoluminescence spectra of exciton polaritons in GaN homoepitaxial layers, grown by metalorganic chemical-vapor deposition on single crystals, are reported. Polariton modes involving excitons $A,$ $B,$ $C,$ which correspond to split valence bands ${\ensuremath{\Gamma}}_{9},$ ${\ensuremath{\Gamma}}_{7},$ ${\ensuremath{\Gamma}}_{7}$ symmetries, resolved. Energies the transverse found be, respectively: ${E}_{\mathrm{TA}}=3.4767\mathrm{eV},$ ${E}_{\mathrm{TB}}=3.4815\mathrm{eV}$ ${E}_{\mathrm{TC}}=3.4986\mathrm{eV},$ at temperature $T=1.8\mathrm{K}.$ The shape measured emission depends upon donor concentration. This is explained terms interbranch polariton scattering.