Monte Carlo simulation of terahertz generation innitrides

Abstract

The conditions for microwave power generation under thequasi-periodic motion of carriers caused by the combined action ofcarrier acceleration in a constant electric field and optical phononemission at low temperatures are analysed by means of Monte Carlosimulations of both small- and large-signal responses in bulknitrides such as GaN and InN. It is shown that, as a consequence ofthe high value of the optical phonon energy and the strongelectron-phonon interaction, a dynamic negative differentialmobility caused by transit-time resonance occurs over a wide frequencyrange which covers practically the whole submillimetre range andpersists in the THz frequency range up to liquid nitrogentemperature. The efficiency of the amplification and generation isfound to depend nonmonotonically on: (i) the static and microwaveelectric field amplitudes, (ii) the generation frequency, and(iii) the carrier concentration. Accordingly, for each generationfrequency there exists an optimal range of parameter values. Underoptimal conditions we predict a generation efficiency of about1-2% in the 0.5-1.5 THz frequency range.