Excitation of Short Electric Monopulse in Nitride Films with Negative Differential Conductivity

Abstract

The excitation of short electric monopulses of space charge waves with wide frequency spectrum of terahertz range in nitride films has been theoretically investigated. The excitation of these pulses with duration ≤ 5 ps and high peak values of electric fields is possible in n-GaN or n-InN films of submicron thickness in the presence of negative differential conductivity. The simulation of nonlinear dynamics of pulses was performed with due regard for the nonlocal dependence of the drift electron velocity on the average electron energy. Optimal values of the applied constant electric fields and equilibrium electron concentration for excitation of monopulses are specified. The monopulse dynamics is weakly dependent on the film width and also on the value and waveform of input excitation pulses. Short electric monopulses differ from domains of strong electric field in Gunn diodes built on bulk crystals with negative differential conductivity.