Unipolar barrier dual-band infrared detectors

Patent metadata

Field	Value
Publication number	US-9799785-B1
Application number	US-201614998990-A
Country	US
Kind code	B1
Filing date	Mar 14, 2016
Priority date	Mar 13, 2015
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

Dual-band barrier infrared detectors having structures configured to reduce spectral crosstalk between spectral bands and/or enhance quantum efficiency, and methods of their manufacture are provided. In particular, dual-band device structures are provided for constructing high-performance barrier infrared detectors having reduced crosstalk and/or enhance quantum efficiency using novel multi-segmented absorber regions. The novel absorber regions may comprise both p-type and n-type absorber sections. Utilizing such multi-segmented absorbers it is possible to construct any suitable barrier infrared detector having reduced crosstalk, including npBPN, nBPN, pBPN, npBN, npBP, pBN and nBP structures. The pBPN and pBN detector structures have high quantum efficiency and suppresses dark current, but has a smaller etch depth than conventional detectors and does not require a thick bottom contact layer.

First claim

What is claimed is:

1. A detector structure comprising:
an electron unipolar barrier having first and second sides;
a first absorber disposed on the first side of the unipolar barrier and comprising at least a first absorber structure formed from at least a first absorber material having a first bandgap;
a second absorber disposed on the second side of the unipolar barrier and comprising at least a second absorber structure formed from at least a second absorber material having a second bandgap and being, wherein the second bandgap is narrower than the first bandgap;
wherein the valence band edges of the unipolar barrier and first and second absorbers are configured to minimize offset therebetween;
wherein at least one of the first and second absorbers comprises an absorber structure formed from an n-type absorber material, and wherein at least one of the first and second absorbers comprises an absorber structure formed from a p-type absorber material; and
wherein that thicknesses of each of the absorber structures of the first and second absorbers are less than the characteristic diffusion length of the absorber material from which the respective absorber structure is formed.

2. The detector structure of claim 1 , wherein at least one of the first or second absorbers is multi-segmented comprising at least two absorber structures, wherein one of the absorber structures is formed from an n-type absorber material and one of the absorber structures is formed from a p-type absorber material.

3. The detector structure of claim 2 , further comprising at least one graded-gap transition region being disposed between the absorber structures of the multi-segmented absorber and configured to minimize offset between the band edges of the individual segments of the multi-segmented absorber.

4. The detector structure of claim 1 , wherein both the first and second absorbers are multi-segmented each comprising at least two absorber structures, wherein one of the absorber structures is formed from an n-type absorber material and one of the absorber structures is formed from a p-type absorber material.

5. The detector structure of claim 4 , further comprising at least one graded-gap transition region being disposed between the segments of each of the multi-segmented absorbers and configured to minimize offset between the band edges of the individual segments of each of the multi-segmented absorbers.

6. The detector structure of claim 1 , wherein the unipolar barrier is graded.

7. The detector structure of claim 1 , wherein the unipolar barrier is ungraded and further comprising at least one graded-gap transition region being disposed between the unipolar barrier and one of either the first or second absorber, and configured to minimize offset between the valence band edges of the absorber and the unipolar barrier.

8. The detector structure of claim 1 , further comprising a contact layer disposed distal to each of the absorbers; and
further comprising at least one graded-gap transition region being disposed between at least one of the contact layers and one of either the first or second absorber, and configured to minimize offset between the band edges of the absorber and the contact layer.

9. The detector structure of claim 1 , further comprising at least one graded-gap transition region being disposed within the detector structure and configured to minimize offset between the valence band edges of one or more absorbers to the barrier layer;
wherein the graded-gap comprises a superlattice formed from a plurality of repeated layers of at least two semiconductor materials, each layer being defined by a layer thickness such that each superlattice has a period defined by the combined thicknesses of the plurality of repeated layers; and
wherein the energy band gap structure of each superlattice including the band gap, conduction band edge and the valence band edge depends on the composition, thickness and period of the plurality of the repeated layers.

10. The detector structure of claim 1 , wherein both the first and second absorbers each comprise at least one absorber structure formed of a p-type absorber material and at least one absorber structure formed of an n-type absorber material.

11. The detector structure of claim 1 , wherein the first absorber comprises at least one absorber structure formed of a p-type absorber material and at least one absorber structure formed of an n-type absorber material, and wherein the second absorber comprises a single absorber structure formed of one of either an n-type or a p-type absorber material.

12. The detector structure of claim 1 , wherein the second absorber comprises at least one absorber structure formed of a p-type absorber material and at least one absorber structure formed of an n-type absorber material, and wherein the first absorber comprises a single absorber structure formed of one of either an n-type or a p-type absorber material.

13. The detector structure of claim 1 , wherein the first and second absorbers are each different and each comprise a single absorber structure formed of one of either an n-type or a p-type absorber material.

14. The detector structure of claim 1 , wherein the n-type absorber structures are formed from a graded-gap material.

15. The detector structure of claim 1 , further comprising at least one contact layer disposed on the side of each absorber distal to the unipolar barrier, and wherein the contact layers are formed of a doped n-type material and have a wider band gap material than the band gap of the adjacent absorber.

16. The detector structure of claim 15 , further comprising graded-gap transition regions between either of the absorbers and the adjacent contact layer and configured to allow the free flow of electrons therebetween.

17. The detector structure of claim 1 , further comprising a contact layer disposed distal to each of the absorbers; and
further comprising a hole unipolar barrier between either of the absorbers and the adjacent contact layer.

Assignees

• California Inst Of Techn

Inventors

• Ting David Z
• Soibel Alexander
• Khoshakhlagh Arezou
• Gunapala Sarath

Classifications

• H01L31/035236 Primary

  Electricity · mapped topic

• H01L31/03046

  Electricity · mapped topic

• H01L31/109

  Electricity · mapped topic

• H01L31/1844

  Electricity · mapped topic

• H10F77/1248

  having three or more elements, e.g. GaAlAs, InGaAs or InGaAsP · CPC title