High-frequency fall-off of Impatt diode efficiency

TLDR: In this article, the performance of Si and GaAs abrupt junction Impatt diodes is studied with a Read type analysis and it is found that the Si p+n abrupt junction diode remains essentially the same up to about 100 GHz and starts to degrade appreciably beyond that.

Abstract: Large-signal operation of Si and GaAs abrupt junction Impatt diodes is studied with a Read type analysis. Modifications are made to the existing Read type analysis to take into account a finite width of the avalanche region. Read's original assumption of a constant total particle current in the avalanche region is kept. A series of diodes with varying space charge layer widths are analyzed at typical operating conditions respectively. It is found, under many simplifying assumptions, that oscillation efficiency of the Si p+n abrupt junction diode remains essentially the same up to about 100 GHz and starts to degrade appreciably beyond that. The cause is the saturation of ionization rates at high electric field. The GaAs diode is found to perform better up to 50 GHz but become comparable beyond 100 GHz. Experimental data in the literature indicate that the tunnel current has practically no effect even in the 0·1 μm Si diode, which is the narrowest studied. This seems to be the case with the GaAs diode too.