Physical Mechanisms in High Efficiency Gallium Arsenide Avalanche Diodes

Anomalously high efficiencies have been observed in GaAs avalanche diode structures - approaching twice that predicted for the ideal Read diode. The physical mechanisms which contribute to this observed efficiency enhancement, namely depletion layer width modulation and accelerated carrier flow, are described in this paper. The principles are established using a sharp pulse model, and the discussion is extended to consider the implications for broad pulses. The validity of the analytical approaches is then assessed by comparing the results of analysis with those of a computer simulation of the device, including all the relevant device physics.