Transient Monte Carlo Simulation of Heterojunction Microwave Oscillators

We have performed self-consistent ensemble Monte Carlo simulations of GaAs Gunn oscillators to understand how the heterojunction cathode affects the RF performance. We compare two heterojunction cathode oscillators (x=0.23 and z=0.33) to the notch oscillator. We find that the dead zone corresponding to x=0.33 is significantly lower, but this reduction does not produce a corresponding improvement in RF performance relative to the notch oscillator. Moreover, the domain is able to mature so we observe a traveling dipole layer. When the Al mole fraction is decreased to 0.23, we find that the length of the dead zone is almost equal to the notch oscillator and the RF performance is comparable to the notch oscillator. Also, the domain is in the translt accumulation mode, similar to the notch oscillator.