Unipolar barrier dual-band infrared detectors

• US 9,799,785 B1
• Filed: 03/14/2016
• Issued: 10/24/2017
• Est. Priority Date: 03/13/2015
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Ting, David Z., Soibel, Alexander, Khoshakhlagh, Arezou, Gunapala, Sarath
• Primary Examiner(s): Han, Jonathan
• Application Number:
  US14/998,990
• Time in Patent Office: 589 Days
• Field of Search: 257E31033, 257184, 257 21, 257E31067, 438 94
• CPC Class Codes: H01L 31/03046 including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
• CPC Class Codes: H01L 31/035236 Superlattices; Multiple quantum well structures
• CPC Class Codes: H01L 31/1013 devices sensitive to two or more wavelengths, e.g. multi-spectrum radiation detection devices
• CPC Class Codes: H01L 31/109 the potential barrier being of the PN heterojunction type
• CPC Class Codes: H01L 31/1844 comprising ternary or quaternary compounds, e.g. Ga Al As, In Ga As P
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

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.

Claims

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.