Femtosecond Switching of Electron and Phonon Streams in Gallium Nitride Crystals

Ensemble Monte Carlo method is employed for the study of electron and phonon system in cubic GaN crystals subjected to femtosecond electric field pulses. Transient response is considered at the lattice temperatures of 15 and 300 K. THz electromagnetic wave emission by the transient electron drift response is found to be more effective at 300 K than at low temperatures. Contrary to it, low temperatures are favourable for creating the LO phonon band population inversion with respect to the acoustic one. Phonon band population inversion can give rise to the stimulated emission of THz photons