Electron-phonon interactions in the wide band-gap semiconductor GaN

Picosecond Raman spectroscopy has been employed to study electron-phonon interactions in the wide band-gap semiconductor GaN. By using very intense picosecond laser pulses in the visible spectral range, electron-hole pairs were generated through the two-photon absorption in GaN. The relaxation of these high energy electrons and holes were used to interrogate electron-phonon interactions. We have found that electrons thermalize toward the bottom of the conduction band by emitting primarily longitudinal optical phonons. Our work demonstrates that the Fröhlich interaction is much stronger than the deformation potential interaction in wurtzite GaN.