Operation of GaAs P+PNN+ Avalanche-Diodes at High Current Densities for Pulsed Millimetre Wave Oscillators

The large-signal operation of GaAs p+pnn+ avalanche-diodes at high current densities, which is different from conventional Impatt-mode operation, has been investigated for millimetre wave frequencies. Current densities as high as necessary for large-signal avalanche resonance and even higher lead to superimposed drift and avalanche processes which are distributed over the total active region of the device. The effects of this operation mode on the DC-stability and power generation are discussed. The theoretical calculations demonstrate the operation mechanism and are compared with experimental results. With optimized pn-doping efficiencies up to 17% and output power near 100W are predicted at 60GHz with a negative rf-resistance of 10hm. Experimental power densities of 160kW/cm2 reach nearly the theoretical curve at a current density of 90kA/cm2.