Invited review - Superlattice and multiquantum well avalanche photodetectors: physics, concepts and performance

In this paper we review the underlying physical principles behind the workings of superlattice/multiquantum well avalanche photodiodes (APDs), examine various device concepts that have been proposed and developed, and discuss their performance. The basic operation, noise and frequency performance of APDs is discussed both in general and as applied to superlattice/multiquantum well devices. The theory of the impact ionization enhancement across a potential step is reviewed. Both experimental and theoretical studies of the ionization enhancement in the simple and doped multiquantum well APDs are discussed, and the progress to date in their realization is reviewed. We conclude with a summary of the performance features of these devices, including a discussion of device reliability and edge breakdown avoidance. (C) 2000 Academic Press.