PHOTODETECTOR WITH DARK CURRENT REDUCTION

摘要

A detector of incident infrared radiation has a first region with a first spectral response, and a second region with a second, different spectral response. The second absorption region is stacked on the first and may be separated therefrom by a region in which the chemical composition of the compound semiconductor is graded. Separate contacts are provided to the first and second absorption regions and a further common contact is provided so as to permit the application of either a bias voltage or a skimming voltage across the respective pn junctions. The detector may be operated such that a preselected one of the absorption regions responds to incident infrared radiation of a predetermined waveband while the other absorption region acts as a skimmer of dark current, thereby enhancing the signal to noise ratio of the detector.