Abstract: A multi-layer semiconductor diode having a layer of wide bandgap material located between the active layer and a first contact zone, where the active layer and additional wide bandgap layer are of one dopant type, and the first contact zone is of the opposite dopant type. A specific embodiment of the invention comprises a stack formed from a first contact zone (4) of p-type material, a lightly doped p-type active layer (2), an additional p layer (20) and a second contact zone (6) of n-type material. The diode may be used as an infrared detector or a negative luminescent source.

Abstract: A multi-layer semiconductor diode having a layer of wide bandgap material located between the active layer and a first contact zone, where the active layer and additional wide bandgap layer are of one dopant type, and the first contact zone is of the opposite dopant type. A specific embodiment of the invention comprises a stack formed from a first contact zone (4) of p-type material, a lightly doped p-type active layer (2), an additional p layer (20) and a second contact zone (6) of n-type material. The diode may be used as an infrared detector or a negative luminescent source.

Abstract: An infrared optical system incorporates a lens for imaging a remote scene onto a detector within a cold shield. Stray radiation incident on the detector is reduced by an optical stop in the form of a light emitting diode producing negative luminescence. The LED emits less radiation than background, and contributes less to the detector photon noise than an optical stop not exhibiting negative luminescence.

Abstract: A single three-electrode linear detector replaces the conventional series or parallel linear detector array in a scanned image thermal detection system. The detector comprises an elongated semiconductor/photoconductor strip, typically 0.25 cm long and 50 .mu.m wide, e.g., of cadmium mercury telluride. A bias current in the strip is arranged to give a photocarrier drift velocity in the strip which matches the image scanning velocity thereby giving enhanced image resolution. Modulation in photocarrier current which constitutes the detected image is measured as a bulk resistivity change between two readout electrodes positioned near one end of the strip.