Observation of a peak in the negative-resistance/r.f.-voltage curve for high-low GaAs impatt diodes

We have observed experimentally a peak in the negative-resistance/r.f.-voltage curve in gallium-arsenide high-low impatt diodes for the first time. We have therefore tried to correlate this effect with the theory of the premature collection mode. This theory explained the high efficiency observed experimentally in GaAs impatt diodes with low-high-low structures in terms of a more favourable carrier transit angle accompanied by an increase of microwave output power at high r.f. voltages. This type of behaviour also occurs in the high-low high-efficiency GaAs impatts we have studied. Simultaneously, we performed a computer simulation on similar diodes, and these calculations confirm the observed peak and its dependance on the maximum efficiency and physical parameters.