Monte Carlo simulation of the generation of terahertz radiation in GaN

The conditions for microwave power generation at low temperatures under opt ical phonon emission are analyzed by Monte Carlo simulations of both small- and large-signal responses in bulk zinc blende and wurtzite GaN. As a resu lt of the high optical phonon energy and the strong interaction of electron s with optical phonons in GaN a general improvement on the transit-time res onance and a considerable increase in the maximum generation frequency and power can be achieved in comparison to the widely studied III-V materials s uch as GaAs and InP. A dynamic negative differential mobility caused by tra nsit-time resonance occurs in a wide frequency range of about 0.05-3 THz an d persists in the THz frequency range up to the liquid nitrogen temperature with doping levels up to about 5x10(16) cm(-3). The efficiency of the ampl ification and generation is found to depend nonmonotonously on static and m icrowave electric field amplitudes, generation frequency, and doping level so that for each generation frequency there exists an optimal range of para meter values. Under optimal conditions a generation efficiency of about 1% to 2% can be achieved in the 0.5-1.5 THz frequency range. (C) 2001 American Institute of Physics.