Planar P-I-N photodetectors

DETAILED DESCRIPTION In accordance with an illustrative embodiment of my invention, a photodetector includes a semi-insulating single crystal body of light-absorbing semiconductor material and spaced-apart, single crystal p- and n-type zones integrally and electrically coupled to a major surface of the body.
The zones, which may be mesas epitaxially grown on the surface or regions diffused or ion-implanted into the surface, are positioned so that light absorbed between the zones generates photocarriers which are able to move (diffuse and/or drift) to the zones and generate a photovoltage thereacross.
The distance separating these zones differs depending on whether the device is to function as a solar cell or as a signal detector, but in either case is not greater than the sum of the diffusion lengths of holes and electrons in the light-absorbing material.