Amplification of Space Charge Waves of Millimeter Wave Range in N-Gan Films

Spatial amplification of millimeter wave range (f = 30 - 200 GHz) space charge waves in n-GaN films is investigated theoretically. An amplification is due to the negative differential conductivity in 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. There no principal difference between these two approaches in the frequency range f≤150 GHz.