Small-signal analysis of a p-n junction avalanche diode having a uniform avalanche zone and a drift zone for unequal ionization rates and drift velocities of electrons and holes

A small-signal analysis of a p-n junction in breakdown is presented. The space-charge region consists of two layers, one a constant avalanche multiplication layer and the other a drift layer. The ionization rates and drift velocities for electrons and holes are considered to be different but the respective ratios are assumed to be constant and independent of field within the normal range of operation of the diode. The diode admittance and negative Q are plotted against frequency for silicon, germanium and GaAs for two structures having avalanche regions of different widths including one resembling a Read-type structure.