Amplification of space charge waves of short wave part of millimeter wave range in n-GaN films

An amplification of space charge waves (SCW) due to the negative differential conductivity in n-GaN films placed onto a semi-infinite substrate is considered and possible spatial increments are calculated. Both diffusion-drift equations for volume electron concentration and also an approximation of two-dimensional electron gas were used jointly with the Poisson equation for the electric field. When compared with a case of the n-GaAs film, it is possible to observe an amplification of SCW in n-GaN films of submicron thicknesses at essentially higher frequencies f ges 100 GHz. It is possible to obtain high (~10 kV/cm) output electric fields of the short wave part of the millimeter wave range. Direct numerical simulations of nonlinear equations of motion confirm the results of calculations of spatial increments in the film of a finite thickness.