Patent ID: 7755023

Claim:
A photon detector comprising: a semiconductor graded absorber layer adapted to photo-generate charge carriers, the graded absorber layer having a composition grade; a semiconductor collector layer adapted to collect the photo-generated charge carriers; and a semiconductor selector layer adapted to selectively deplete the absorber layer, the selector layer having a same doping type as the collector layer and an opposite doping type as the absorber layer, wherein the composition grade of the absorber layer is away from the selector layer such that a narrower band gap absorber material is closer to the collector layer and a wider band gap absorber material is closer to the selector layer, wherein the electromagnetic radiation to be detected enters the absorber layer through the selector layer, wherein a p/n junction composed of the selector layer and the absorber layer is configured to change the spectral response of the detector in accordance with the magnitude of a reverse bias applied to the p/n junction, wherein the graded absorber layer is interposed between the collector layer and the selector layer, wherein the graded absorber layer contacts the collector layer and the selector layer, and wherein independent electrical contacts are made to the selector layer, the absorber layer and the collector layer.