High resistance photoconductor structure for multi-element infrared detector arrays

DETAILED DESCRIPTION In accordance with the above requirements, the present invention, a high resistance thin film photoconductive detector structure is constructed comprising layers of p-doped and n-doped mercury cadmium telluride.
This structure is intended for use in hig density, multi-element detector arrays providing high resistance detectors and facilitating coupling to focal plane read-out circuits like charge coupled devices.
Specifically, for high resistance photoconductors; coupling can be achieved by gate injection into charge coupled devices where the voltage change across the photoconductive detector will modulate a potential level of a gate in a fill and spill type charge coupled device input structure.
No amplifiers are necessary between the charge coupled device's input port and the high resistance photoconductive detector; thereby achieving low power and simplicity in the detector read-out circuits.
This high resistance photocondutive (HRPC) detector structure consists of n-type mercury cadmium telluride infrared photosensitive layer disposed between two blocking regions; where said blocking regions confine the electrons and holes within the infrared photosensitive layer.
The blocking regions are transparent to infrared radiation and prevent any substantial number of electrons or holes from leaving and/or entering the infrared photosensitive layer.
The entire three-layer structure is formed on a semiconductor substrate for mechanical support.
An infrared transparent substrate is preferable, because it offers the possibility of backside illumination of the HRPC detector.
Two N+ doped contact regions areas, located in the n-type mercury cadmium telluride infrared photosensitive layer, provide two terminals for read-out of the high resistance photoconductive infrared detector.
Finally, a conductive layer is disposed on the front side of this detector structure and the substrate becomes the backside of the high resistance photoconductive detector.
In some high resistance photoconductive detector embodiments, a thin conducting layer may be inserted between the substrate and the blocking region beneath the n-type HgCdTe photosensitive layer