Excitation of short monopulses in nitride films under negative differential conductivity

It is investigated theoretically the excitation of short monopulses of space charge waves with a wide spectrum in THz range due to the negative differential conductivity in nitride films of submicron thicknesses. In n-GaN and n-InN films it is possible to generate the pulses of ≤5 ps
^durations
of high values of the electric field. The influence of the nonlocal dependence of the average electron velocity on the electron energy is taken into account. The optimum values of the bias electric fields and the doping concentrations for generating short monopulses are obtained. The short monopulses can be generated without any pedestal and differ from the domains of the strong electric field in the volumetric crystals.