URBACH-MARTIENSSEN TAILS IN A WURTZITE GAN EPILAYER

Effects of an interaction between the electronic and lattice systems o n the optical spectra of a wurtzite GaN epilayer were investigated, Th e exponentially increasing absorption tail was well explained as an Ur bach-Martienssen tail, giving the characteristic phonon energy of 30 m eV. The result indicates that few longitudinal optical phonons contrib ute to the exciton-phonon coupling even at room temperature. (C) 1997 American Institute of Physics.