Abstract

Multiplication via impact ionization of secondary carriers in interband ionization avalanche photodiodes results in significant degradation of the excess noise factor and bandwidth of the device. Alternatively, solid state photomultipliers which exploit impact ionization out of confined quantum states offer ultralow noise and high speed performance since they operate as unipolar devices thereby avoiding the occurrence of secondary ionization. As a consequence, much lower noise and high speed performance is anticipated in these devices. We present calculations of the gain, dark current, and gain to dark current ratio in confined quantum state photomultipliers made from the GaAs/AlGaAs material system. Our model calculations are based on the average ionization rate calculated from the quantum mechanical transition rate assuming a drifted Maxwellian initial carrier distribution. It is found that the highest gain at lowest dark current is achieved in an asymmetric quantum well structure in which the second barrier height is half as large as the initial barrier height.

© 1989 Optical Society of America