Single-band and dual-band infrared detectors
Bias-switchable dual-band infrared detectors and methods of manufacturing such detectors are provided. The infrared detectors are based on a back-to-back heterojunction diode design, where the detector structure consists of, sequentially, a top contact layer, a unipolar hole barrier layer, an absorber layer, a unipolar electron barrier, a second absorber, a second unipolar hole barrier, and a bottom contact layer. In addition, by substantially reducing the width of one of the absorber layers, a single-band infrared detector can also be formed.
1. A bias-switchable dual-band infrared detector comprising:
first and second contact structures;
a first unipolar electron barrier layer adjacent to said first contact layer, and a second unipolar electron barrier layer adjacent said second contact layer;
a first absorber layer adjacent to said first unipolar electron barrier layer, and a second absorber layer adjacent to said second unipolar electron barrier layer;
a unipolar hole barrier layer disposed between said first and second absorber layers; and
wherein the hole unipolar barrier is configured to block the flow of minority carriers between the first and second absorber layers.
2. The bias-switchable dual-band infrared detector of claim 1 wherein the first contact layer, first unipolar electron barrier layer and first absorber layers are configured such that there is minimal valence band edge offset among them, wherein the second contact layer, second unipolar electron barrier layer and second absorber layers are configured such that there is minimal valence band edge offset among them, and wherein the first absorber layer, unipolar hole barrier layer and second absorber layers are all configured such that the conduction band edges of said layers are closely aligned.
3. The bias-switchable dual-band infrared detector of claim 1 wherein both of the absorber layers are n-type doped.
4. The bias-switchable dual-band infrared detector of claim 1 wherein both of the contact layers are p-type doped.
5. The bias-switchable dual-band infrared detector of claim 1 wherein the first and second unipolar electron barrier layers are configured to block the flow of majority carriers from the absorber.
6. The bias-switchable dual-band infrared detector of claim 1 wherein the unipolar electron barrier layers are one of undoped, n-type doped, or have a graded doping profile that varies n-type near the adjacent absorber layer to p-type adjacent the contact layer.
7. The bias-switchable dual-band infrared detector of claim 1 wherein one grouping of layers selected from the group consisting of the first absorber layer and first contact layers, the second absorber layer and second contact layers, the first electron barrier layer and first contact layers, and the second electron barrier layer and second contact layers are formed from the same material.
8. The bias-switchable dual-band infrared detector of claim 1 wherein the width of one of either the first or second absorber layers is reduced such that the infrared detector operates as a single-band detector, wherein the detection characteristics of the detector are solely determined by the thicker of the absorber layers.
9. The single-band infrared detector of claim 8 wherein the gain of the detector is dependent on the height of the unipolar hole barrier layer.