Heterojunction photovoltaic device and fabrication method

Patent metadata

Field	Value
Publication number	US-11094842-B2
Application number	US-201916285688-A
Country	US
Kind code	B2
Filing date	Feb 26, 2019
Priority date	Jul 29, 2011
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A photovoltaic device and method include a doped germanium-containing substrate, an emitter contact coupled to the substrate on a first side and a back contact coupled to the substrate on a side opposite the first side. The emitter includes at least one doped layer of an opposite conductivity type as that of the substrate and the back contact includes at least one doped layer of the same conductivity type as that of the substrate. The at least one doped layer of the emitter contact or the at least one doped layer of the back contact is in direct contact with the substrate, and the at least one doped layer of the emitter contact or the back contact includes an n-type material having an electron affinity smaller than that of the substrate, or a p-type material having a hole affinity larger than that of the substrate.

First claim

What is claimed is:

1. A multi-junction photovoltaic device comprising:
a top cell including a photovoltaic cell configured to initially receive light;
a tunnel layer disposed between the top cell and a bottom cell; and
the bottom cell comprising:
a germanium-containing substrate coupled to an emitter contact on a front side of the substrate and a back contact on a back side of the substrate, with the emitter contact being disposed between the substrate and the tunnel layer;
at least one doped layer in the back contact comprised of an n-type material having an electron affinity smaller than that of the germanium-containing substrate, or a p-type material having a hole affinity larger than that of the germanium containing substrate; and
a passivation layer in direct contact with the at least one doped layer and a transparent conductive material.

2. The device as recited in claim 1 , wherein the at least one doped layer of the back contact includes single crystalline SiGe.

3. The device as recited in claim 1 , wherein the at least one doped layer of the back contact includes crystalline SiGe and the passivation layer is formed in contact with the at least one doped layer and the substrate, the passivation layer including amorphous SiGe.

4. The device as recited in claim 1 , wherein the substrate includes p-type crystalline Ge or p-type crystalline SiGe; the emitter contact includes an amorphous SiC doped layer and an amorphous SiC passivation layer; and the back contact includes a SiGe doped layer and an amorphous SiGe passivation layer.

5. The device as recited in claim 1 , further comprising a passivation layer in contact with the at least one doped layer of the emitter contact or the back contact.

6. The device as recited in claim 1 , wherein the back contact includes at least one of an intrinsic layer, a doped layer, and a conductive layer.

7. The device as recited in claim 1 , wherein the top cell includes a cell having one or more of a III-V material cell, a p-i-n stack, multiple p-i-n stacks, a CdS/CdTe cell, CdS/CIGS (copper indium gallium selenide) cell, a CdS/CZTS (copper zinc tin sulfide) cell, and a CdS/CZTSe (copper zinc tin selenide) cell.

8. A multi-junction photovoltaic device comprising:
a top cell including a photovoltaic cell configured to initially receive light;
a tunnel layer disposed between the top cell and a bottom cell; and
the bottom cell comprising:
a doped germanium-containing substrate;
an emitter contact coupled to the substrate on a first side, with the emitter contact being disposed between the substrate and the tunnel layer; and
a back contact coupled to the substrate on a side opposite the first side;
the emitter including at least one doped layer of an opposite conductivity type as that of the substrate and the back contact including at least one doped layer of the same conductivity type as that of the substrate;
wherein the at least one doped layer of the emitter contact or-the at least one doped layer of the back contact is in direct contact with the substrate and an intrinsic passivation layer, and the at least one doped layer of the emitter contact or the back contact includes an n-type material having an electron affinity smaller than that of the substrate, or a p-type material having a hole affinity larger than that of the substrate.

9. The device as recited in claim 8 , wherein the at least one doped layer of the emitter contact or the back contact includes one of SiC and single crystalline SiGe.

10. The device as recited in claim 8 , wherein the at least one doped layer of the emitter contact or the back contact includes crystalline SiGe and a passivation layer is formed in contact with the at least one doped layer that includes the crystalline SiGe and the substrate, the passivation layer including amorphous SiGe.

11. The device as recited in claim 8 , wherein the at least one doped layer of the emitter contact or the back contact includes amorphous SiC and a passivation layer is formed in contact with the at least one doped layer that includes the amorphous SiC, the passivation layer including amorphous SiC.

12. The device as recited in claim 8 , wherein the substrate includes n-type crystalline Ge or n-type crystalline SiGe; the emitter contact includes a SiGe doped layer and an amorphous SiGe passivation layer; and the back contact includes an amorphous SiC doped layer and an amorphous SiC passivation layer.

13. The device as recited in claim 8 , wherein the substrate includes p-type crystalline Ge or p-type crystalline SiGe; the emitter contact includes an amorphous SiC doped layer and an amorphous SiC passivation layer; and the back contact includes a SiGe doped layer and an amorphous SiGe passivation layer.

14. The device as recited in claim 8 , further comprising a passivation layer in contact with the at least one doped layer of the emitter contact or the back contact.

15. The device as recited in claim 8 , wherein the back contact includes at least one of an intrinsic layer, a doped layer and a conductive layer.

16. The device as recited in claim 8 , wherein the top cell includes a cell having one or more of a III-V material cell, a p-i-n stack, multiple p-i-n stacks, a CdS/CdTe cell, CdS/CIGS (copper indium gallium selenide) cell, a CdS/CZTS (copper zinc tin sulfide) cell, and a CdS/CZTSe (copper zinc tin selenide) cell.

17. The device as recited in claim 1 , wherein the passivation layer is doped.

Assignees

• IBM

Inventors

• Bedell Stephen W
• Fogel Keith E
• Hekmatshoar-Tabari Bahman
• Sadana Devendra K
• Shahidi Ghavam G
• Shahrjerdi Davood

Classifications

• H10F77/1226

  comprising multiple Group IV elements, e.g. SiC · CPC title

• H10F10/148

  Double-emitter photovoltaic cells, e.g. bifacial photovoltaic cells · CPC title

• H10F77/311

  for photovoltaic cells · CPC title

• H10F77/219

  Arrangements for electrodes of back-contact photovoltaic cells · CPC title

• H10F71/1215

  comprising at least two Group IV elements, e.g. SiGe · CPC title