Short wavelength impurity band conduction detectors

Abstract

An edge illuminated impurity band conduction detector includes an extrinsic semiconducting IR-active layer with a first conductivity type impurity concentration high enough to create an impurity energy band. An intrinsic semiconducting blocking layer includes first and second conductivity type impurity concentration low enough that substantially no charge transport occurs by an impurity conduction mechanism. The IR-active and blocking layers are positioned between first and second contacts such that an electrical potential applied to the contacts creates an electric field across the layers. The detector is oriented such that the electromagnetic energy impinges on an edge of the IR-active layer and propagates in the IR-active layer in a direction substantially orthogonal to the applied electric field, the IR-active layer extending in the orthogonal direction for at least the absorption length of the electromagnetic energy. The detector may further include an extrinsic semiconducting buffered layer positioned with the IR-active layer between the blocking layer and the buffered layer, the buffered layer having a first conductivity type impurity concentration high enough to create an impurity energy band and a second conductivity type impurity concentration high enough that first conductivity type carriers injected into the buffered layer recombine with ionized first conductivity type impurities. In this embodiment, the IR-active layer further includes a second conductivity type impurity concentration low enough that first conductivity type carriers photogenerated in the IR-active layer can drift through the IR-active layer without recombining with ionized first conductivity type impurities.