CdTe-based double heterostructures and related light-conversion devices

Patent metadata

Field	Value
Publication number	US-10396232-B2
Application number	US-201716090033-A
Country	US
Kind code	B2
Filing date	Mar 29, 2017
Priority date	Mar 31, 2016
Publication date	Aug 27, 2019
Grant date	Aug 27, 2019

Abstract

Devices converting light to electricity (such as solar cells or photodetectors) including a heavily-doped p-type a-SiC y :H and an i-Mg x Cd 1-x Te/n-CdTe/N—Mg 0.24 Cd 0.76 Te double heterostructure (DH), with power conversion efficiency of as high as 17%, V oc as high as 1.096 V, and all operational characteristics being substantially better than those of monocrystalline solar cells known to-date. The a-SiC y :H layer is configured to enable high built-in potential while, at the same time, allowing the doped absorber to maintain a very long carry lifetime. In comparison, similar undoped CdTe/Mg x Cd 1-x Te DH designs reveal a long carrier lifetime of 3.6 μs and an interface recommendation velocity of 1.2 cm/s, which are lower than the record values reported for GaAs/Al 0.5 Ga 0.5 As (18 cm/s) and GaAs/Ga 0.5 In 0.5 P (1.5 cm/s) DHs.

First claim

What is claimed is:

1. A device configured to convert light to electricity, the device comprising:
an InSb substrate, and
a double-heterojunction (DH) structure carried on said InSb substrate, said DH structure including a CdTe-containing absorber layer sandwiched between first and second MgxCd 1-x Te-containing barrier layers,
wherein the first and second barrier layers are configured to confine minority carriers to said absorber layer, and
wherein said DH structure is characterized by an open-circuit voltage that exceeds 1 V,
and further comprising a layer of a-Si:H on the DH structure, said a-Si:H layer configured as a p-type doped electrical contact layer, and
wherein a barrier layer from the first and second barrier layers contains a spatial doping material profile that is not uniform across the thickness of said barrier layer.

2. The device according to claim 1 , further comprising an electrode layer and a p-typed doped contact layer configured between said electrode layer and said DH structure.

3. The device according to claim 1 , wherein said p-type doped contact layer is a p-aSiC y :H contact layer, wherein a value of y is within a range between zero and 0.5, inclusive of zero.

4. The device according to claim 1 , characterized by an effective radiative lifetime of carriers, in said DH structure, that exceeds 2 microseconds.

5. The device according to claim 1 , characterized by an effective radiative lifetime of carriers, in said DH structure, that exceeds 3 microseconds.

6. The device according to claim 1 , wherein an absolute value of interface recombination velocity (IRV) of carriers in said DH structure is lower than a first IRV of carriers characterizing a first material interface and lower than a second IRV of carriers characterizing a second material interface, the first material interface including a GaAs/Al 0.5 Ga 0.5 As material interface and the second material interface including a GaA/Ga 0.5 In 0.5 P material interface.

7. The device according to claim 1 , wherein an absolute value of IRV of carriers in said DH structure is lower than 1.5 m/s.

8. The device according to claim 1 , wherein said DH structure includes a p-type ZnTe doping material.

9. The device according to claim 1 , further comprising a p-type doped contact layer on said DH structure, said p-type contact layer containing a layer of aSiC y :H and an immediately neighboring aSi:H layer,
wherein y is about 6%,
wherein the first barrier layer is a 10 nm thick undoped Mg 0.30 Cd 0.70 Te barrier layer, the first barrier layer being the closest of the first and second barrier layers to the p-type doped contact layer,
wherein the absorber layer has an approximately 1 micron thickness and is doped with n-type In doping at a level of about 3e 16 cm −3 .

10. The device according to claim 1 , further comprising a p-type doped contact layer on said DH structure, said p-type contact layer including a layer of aSi:H,
wherein the first barrier layer is a 10 nm thick undoped Mg 0.30 Cd 0.70 Te barrier layer, the first barrier layer being the closest, of the first and second barrier layers, to the p-type doped contact layer, and
wherein the absorber layer has an approximately 1.4 micron thickness and is doped with n-type In at a first level of about 1e 16 cm −3 in a first portion of said absorber layer and at a second level of about 5e 17 cm −3 in a second portion of said absorber, the first portion being about 1 micron thick, the second portion being spatially complementary to said first portion.

11. The PV cell according to claim 10 , wherein the second portion of the absorber layer is separated from said contact layer by the first portion of said absorber layer.

12. A device configured to convert light to electricity, the device comprising:
an InSb substrate, and
a double-heterojunction (DH) structure carried on said InSb substrate, said DH structure including a CdTe-containing absorber layer sandwiched between first and second Mg x Cd 1-x Te-containing barrier layers,
wherein the first and second barrier layers are configured to confine minority carriers to said absorber layer, and
wherein a pn-junction is formed outside of the absorber layer,
and further comprising a layer of a-Si:H on the DH structure, said a-Si:H layer
configured as a p-type doped electrical contact layer, and
wherein a barrier layer from the first and second barrier layers contains a spatial doping material profile that is not uniform across the thickness of said barrier layer.

13. A device according to claim 12 , wherein said DH structure is characterized by an open-circuit voltage that exceeds 1 V.

14. A device according to claim 12 , wherein said p-type doped contact layer is a p-aSiC y :H contact layer, wherein a value of y is within a range between and inclusive of zero and 0.5.

15. The device according to claim 12 , characterized by an effective radiative lifetime of carriers, in said DH structure, that exceeds 2 microseconds.

16. The device according to claim 12 , wherein an absolute value of interface recombination velocity (IRV) of carriers in said DH structure is lower than a first IRV of carriers characterizing a first material interface and lower than a second IRV of carriers characterizing a second material interface, the first material interface including a GaAs/Al 0.5 Ga 0.5 As material interface and the second material interface including a GaA/Ga 0.5 In 0.5 P material interface.

17. The device according to claim 12 , wherein at least one of the following conditions is satisfied: (i) an absolute value of IRV of carriers in said DH structure is lower than 1.5 m/s and (ii) wherein said DH structure includes a p-type ZnTe doping material.

18. The device according to claim 12 , further comprising a p-type doped contact layer on said DH structure, said p-type contact layer containing a layer of aSiC y :H and an immediately neighboring aSi:H layer,
wherein y is about 6%,
wherein the first barrier layer is a 10 nm thick undoped Mg 0.30 Cd 0.70 Te barrier layer, the first barrier layer being the closest of the first and second barrier layers to the p-type doped contact layer,
wherein the absorber layer has an approximately 1 micron thickness and is doped with n-type In doping at a level of about 3e 16 cm −3 .

19. The device according to claim 12 , further comprising a p-type doped contact layer on said DH structure, said p-type contact layer including a layer of aSi:H,
wherein the first barrier layer is a 10 nm thick undoped Mg 0.30 Cd 0.70 Te barrier layer, the first barrier layer being the closest, of the first and second barrier layers, to the p-type doped contact layer, and
wherein the absorber layer has an approximately 1.4 micron thickness and is doped with n-type In at a first level of about 1e 16 cm −3 in a first portion of said absorber layer and at a second level of about 5e 17 cm −3 in a second portion of said absorber, the first portion being about 1 micron thick, the second portion being spatially complementary to said first portion.

20. The PV cell according to claim 19 , wherein the second portion of the absorber layer is separated from said contact layer by the first portion of said absorber layer.

Assignees

• Univ Arizona State

Inventors

• Zhang Yong-Hang
• Boccard Mathieu
• Holman Zachary
• Zhao Yuan

Classifications

• Y02E10/543

  Solar cells from Group II-VI materials · CPC title

• H01L31/1836

  Electricity · mapped topic

• H01L31/073 Primary

  Electricity · mapped topic

• H01L31/0445

  Electricity · mapped topic

• H01L31/072

  Electricity · mapped topic