Abstract

The theoretical features of quantum dot infrared photodetectors (QDIP) are very promising, e.g. they absorb light incoming perpendicular to the detectors plane. The discrete spectrum of the density of states results in a relatively long lifetime of excited carriers due to a reduced phonon-electron interaction. The photoconductive gain increases by magnitudes compared to quantum well infrared photodetectors (QWIP) and also the dark current is theoretically reduced significantly due to suppressed thermoionic emission¹. But in fact, there show up some difficulties, e.g. the self organized growth process spreads the dot sizes inhomogeneously whereupon the detectivity of the detectors decreases. This effect cannot be eliminated, but only minimized technologically. The growth of homogeneous InAs quantum dots (QD) on InP is rather problematic since the lattice mismatch between the materials is only 3.2%. If the QD are grown on a InAlGaAs-layer lattice matched to InP their size distribution gets narrower and they get smaller².

© 2007 IEEE