nBn Infrared Detector Containing Graded Absorption Layer

Potential applications include environmental monitoring, firefighting, law enforcement, and medical diagnosis.

It has been proposed to modify the basic structure of an nBn infrared photodetector so that a plain electron-donor-type (n-type) semiconductor contact layer would be replaced by a graded n-type III–V alloy semiconductor layer (i.e., ternary or quarternary) with appropriate doping gradient. The abbreviation “nBn” refers to one aspect of the unmodified basic device structure: There is an electron-barrier (“B”) layer between two n-type (“n”) layers, as shown in the upper part of the figure. One of the n-type layers is the aforementioned photon-absorption layer; the other n-type layer, denoted the contact layer, collects the photocurrent.