Inverted metamorphic multijunction solar cells with doped alpha layer

Patent metadata

Field	Value
Publication number	US-10693029-B1
Application number	US-201715453578-A
Country	US
Kind code	B1
Filing date	Mar 8, 2017
Priority date	Oct 2, 2013
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A method of forming a multijunction solar cell comprising at least a first subcell and a second subcell, the method including forming a first alpha layer over said first solar subcell using a surfactant and dopant including selenium or tellurium, the first alpha layer configured to prevent threading dislocations from propagating; forming a metamorphic grading interlayer over and directly adjacent to said first alpha layer; forming a second alpha layer using a surfactant and dopant including selenium or tellurium over and directly adjacent to said grading interlayer to prevent threading dislocations from propagating; and forming the second solar subcell over said grading interlayer such that the second solar subcell is lattice mismatched with respect to the first solar subcell.

First claim

The invention claimed is:

1. A method of manufacturing a solar cell comprising:
providing a first semiconductor substrate;
depositing on the first semiconductor substrate a sequence of layers of semiconductor material that forms a multijunction solar cell including first and second subcells with different lattice constants, an intermediate grading interlayer positioned between the first and second subcells with a graded lattice constant that matches the first subcell on a first side and the second subcell on the second side, and alpha layers grown in a reactor in the presence of a selenium or tellurium surfactant so that selenium or tellurium is doped into the alpha layers directly on each side of the grading interlayer to minimize threading dislocations from advancing from the grading interlayer into the adjacent first and second subcells, wherein each of the alpha layers has different constituent elements from the respective directly adjacent layer to each alpha layer and wherein each alpha layer is between 0.2 and 0.5 microns in thickness and doped with the selenium or tellurium from 1.0×10 16 free carriers per cubic centimeter to 4.0×10 17 free carriers per cubic centimeter;
mounting a surrogate second substrate on top of the sequence of layers; and
removing the first semiconductor substrate.

2. A method as defined in claim 1 , wherein the grading interlayer is grown in the presence of the selenium or tellurium surfactant.

3. A method as defined in claim 1 , wherein said first subcell is composed of an GaInP, GaAs, GaInAs, GaAsSb, or GaInAsN emitter region and an GaInP, GaAs, GaInAs, GaAsSb, or GaInAsN base region; the second subcell is composed of an InGaAs base and emitter regions, or an InGaP emitter region and a GaAs base region.

4. A method as defined in claim 1 , wherein the grading interlayer material is composed of (In x Ga 1-x ), Al 1-y As with 0<x<1 and 0<y<1, and x and y selected such that the band gap of the interlayer material remains constant throughout its thickness.

5. A method as defined in claim 1 , wherein the selenium is introduced as a precursor gas of di-isopropyl selenide, or the tellurium is introduced as a precursor gas of diethyltellurium or di-isopropyl telluride.

6. A method as defined in claim 1 , wherein said alpha layers have a band gap energy greater than or equal to that of the grading interlayer.

7. A method as defined in claim 1 , wherein said grading interlayer is composed of any of the As, N, Sb based III-V compound semiconductors and has a band gap energy greater than that of the first solar subcell.

8. A method as defined in claim 1 , wherein the alpha layers are composed of any As, P, N or Sb based III-V compound semiconductors having a band gap energy greater than or equal to that of the grading interlayer.

9. A method as defined in claim 1 , wherein the alpha layers include a first alpha layer on one side of the grading interlayer, and a second alpha layer on the other side of the grading interlayer, wherein the second alpha layer has a different composition than the first alpha layer.

10. A method as defined in claim 9 , wherein the second alpha layer is a different thickness than the first alpha layer.

11. A method as defined in claim 9 , wherein the second alpha layer has the same doping as the first alpha layer.

12. A method of manufacturing a solar cell comprising:
providing a semiconductor substrate;
growing on the semiconductor substrate a sequence of layers including first and second subcells with different lattice constants, an intermediate grading interlayer positioned between the first and second subcells with a graded lattice constant that matches the first subcell on a first side and the second subcell on the second side; and
growing alpha layers on both sides of and directly adjacent to the grading interlayer grown in a reactor in the presence of a selenium or tellurium surfactant so that selenium or tellurium is doped into the alpha layer to minimize threading dislocations from advancing from the grading interlayer into the adjacent first and second subcells, wherein each of the alpha layers has different constituent elements from the respective directly adjacent layers to each alpha layer and wherein each alpha layer is between 0.2 and 0.5 microns in thickness and doped with the selenium or tellurium from 1.0×10 16 free carriers per cubic centimeter to 4.0×10 17 free carriers per cubic centimeter.

13. A method as defined in claim 12 , wherein the grading interlayer is also grown in the presence of a selenium or tellurium surfactant.

14. A method as defined in claim 12 , wherein said first subcell is composed of an GaInP, GaAs, GaInAs, GaAsSb, or GaInAsN emitter region and an GaInP, GaAs, GaInAs, GaAsSb, or GaInAsN base region; the second subcell is composed of an InGaAs base and emitter regions, or an InGaP emitter region and a GaAs base region.

15. A method as defined in claim 12 , wherein the grading interlayer is composed of (In x Ga 1-x ), Al 1-y As, with x and y selected such that the band gap of the transition material remains constant throughout its thickness.

16. A method of manufacturing a solar cell comprising:
providing a semiconductor substrate; and
depositing on the semiconductor substrate in a reactor, a sequence of layers of semiconductor material that forms at least a three junction solar cell including first and second subcells with different lattice constants, an intermediate grading interlayer positioned between the first and second subcells with a graded lattice constant that matches the first subcell on a first side and the second subcell on the second side, and first and second alpha layers grown in the reactor in the presence of a selenium or tellurium surfactant so that selenium or tellurium is doped into each of the alpha layers directly on each side of the grading interlayer to minimize threading dislocations from advancing from the grading interlayer into the adjacent first and second subcells, wherein each of the first and second alpha layers has different constituent elements from the respective directly adjacent layers to each alpha layer and wherein each alpha layer is between 0.2 and 0.5 microns in thickness and doped with the selenium or tellurium from 1.0×10 16 free carriers per cubic centimeter to 4.0×10 17 free carriers per cubic centimeter.

17. A method as defined in claim 16 , wherein the grading interlayer is grown in the presence of the selenium surfactant.

18. A method as defined in claim 16 , wherein said first subcell is composed of an GaInP, GaAs, GaInAs, GaAsSb, or GaInAsN emitter region and an GaInP, GaAs, GaInAs, GaAsSb, or GaInAsN base region; the second subcell is composed of an InGaAs base and emitter regions, or an InGaP emitter region and a GaAs base region.

19. A method as defined in claim 16 , wherein the grading interlayer is composed of (In x Ga 1-x ), Al 1-y As with x and y selected such that the band gap of the transition material remains constant throughout its thickness.

Assignees

• Solaero Tech Corp

Inventors

• Cho Benjamin
• Lin Yong
• Patel Pravin
• Stan Mark
• Cornfeld Arthur
• Mcglynn Daniel
• Newman Fred

Classifications

• H10F71/1272

  comprising at least three elements, e.g. GaAlAs or InGaAsP · CPC title

• H10F71/127

  The active layers comprising only Group III-V materials, e.g. GaAs or InP · CPC title

• H10F10/19

  Photovoltaic cells having multiple potential barriers of different types, e.g. tandem cells having both PN and PIN junctions · CPC title

• H10F10/16

  Photovoltaic cells having only PN heterojunction potential barriers · CPC title

• H10F10/13

  Photovoltaic cells having absorbing layers comprising graded bandgaps · CPC title