Monte Carlo simulation of THz maser based on optical phonon transit time resonance in GaN

The linear and nonlinear analysis of microwave power amplification and generation in the terahertz (THz) frequency range is carried out by the Monte Carlo method in bulk wurtzite GaN. It is shown that a dynamic negative differential mobility persists up to 80 K due to the transit-time resonance associated with optical phonons. The generation frequency depends almost linearly on the static electric field strength and can be tuned in the wide frequency range from 0.2 to 3 THz when the electric field varies from 1 up to 12 kV/cm. The optimum amplitude of the microwave electric field generated by bulk GaN is found to be of the order of the static electric field thus leading to a significant maximum efficiency of about 1 to 1.5% for microwave power generation in the THz frequency range.