METHOD AND STRUCTURE FOR FABRICATING SOLAR CELLS USING A LAYER TRANSFER PROCESS

• US 20070235074A1
• Filed: 03/13/2007
• Published: 10/11/2007
• Est. Priority Date: 03/17/2006
• Status: Active Grant

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Henley, Francois, Ong, Philip
• Granted Patent: US 7,863,157 B2
• Time in Patent Office: Days
• US Class Current: 136/252
• CPC Class Codes: H01L 31/0232 Optical elements or arrangements associated with the device H01L31/0236 takes precedence; for photovoltaic cells H01L31/054; for photovoltaic modules H02S40/20
• CPC Class Codes: H01L 31/0392 including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate textured substrates H01L31/02366
• CPC Class Codes: H01L 31/03925 including AIIBVI compound materials, e.g. CdTe, CdS
• CPC Class Codes: H01L 31/0725 Multiple junction or tandem solar cells
• CPC Class Codes: H01L 31/0745 comprising a AIVBIV heterojunction, e.g. Si/Ge, SiGe/Si or Si/SiC solar cells
• CPC Class Codes: H01L 31/077 the devices comprising monocrystalline or polycrystalline materials
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/1872 Recrystallisation
• CPC Class Codes: H01L 31/1892 methods involving the use of temporary, removable substrates
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A photovoltaic cell device, e.g., solar cell, solar panel, and method of manufacture. The device has an optically transparent substrate comprises a first surface and a second surface. A first thickness of material (e.g., semiconductor material, single crystal material) having a first surface region and a second surface region is included. In a preferred embodiment, the surface region is overlying the first surface of the optically transparent substrate. The device has an optical coupling material provided between the first surface region of the thickness of material and the first surface of the optically transparent material. A second thickness of semiconductor material is overlying the second surface region to form a resulting thickness of semiconductor material.

Claims

1. A method for fabricating a photovoltaic cell, the method comprising:

providing a semiconductor substrate, the semiconductor substrate having a surface region, a cleave region and a first thickness of material to be removed between the surface region and the cleave region;

coupling the surface region of the semiconductor substrate to a first surface region of an optically transparent substrate, the optically transparent substrate comprising the first surface region and a second surface region;

cleaving the semiconductor substrate to remove the first thickness of material from the semiconductor substrate, while the surface region remains coupled to the first surface region, to cause formation of a cleaved surface region; and

forming a second thickness of semiconductor material overlying the cleaved surface region to form a resulting thickness of semiconductor material.

2. The method of claim 1 further comprising subjecting the cleaved surface region to a plasma to remove a portion of a hydrogen damaged layer from the cleaved surface region or to activating the surface region and the first surface region before coupling the surface region to the first surface region.

3. The method of claim 1 wherein a process for forming of the second thickness of semiconductor material is selected from a plasma deposition process, a solid phase epitaxy process, and a graphoepitaxy process.

4. The method of claim 1 wherein the forming of the second thickness of semiconductor material comprises forming an amorphous silicon layer.

5. The method of claim 4 further comprises crystallizing the amorphous silicon layer.

6. A photovoltaic cell device comprising:

an optically transparent substrate comprises a first surface and a second surface;

a first thickness of material having a first surface region and a second surface region, the surface region overlying the first surface of the optically transparent substrate;

an optical coupling material provided between the first surface region of the thickness of material and the first surface of the optically transparent material; and

a second thickness of semiconductor material overlying the second surface region to form a resulting thickness of semiconductor material.

7. The device of claim 6 wherein the optical coupling material comprises a tin oxide, indium tin oxide, zinc oxide, or titanium dioxide.

8. The device of claim 6 wherein the first thickness of semiconductor material comprises a single crystal silicon material.

9. The device of claim 6 wherein the optically transparent material comprises a glass substrate, a quartz substrate, or a plastic substrate.

10. The device of claim 6 further comprising a backside cover overlying the second thickness of semiconductor material.

11. A method of fabricating substrates for photovoltaic materials, the method comprising:

providing a donor substrate, the donor substrate including a cleave region, a surface region, and a first thickness of silicon material defined between the cleave region and the surface region;

transferring the first thickness of silicon material to a handle substrate surface region of a handle substrate to detach a portion of the donor substrate within a vicinity of the cleave region and to couple the surface region to the handle substrate surface region of the handle substrate to cause formation of a cleaved surface region overlying the first thickness of silicon material;

supplying a gas including a silane species into a reaction chamber;

using the silane species to cause a silicon deposition condition on the handle substrate surface region of the handle substrate within the reaction chamber using a process selected from one or more including a glow discharge, a plasma, photo-enhanced, or a thermal CVD process; and

forming a second thickness of material, using the silane species overlying the first thickness of silicon material.

12. The method of claim 11 wherein the forming of the second thickness of material is maintained at a temperature ranging from about 650 Degrees Celsius or less.

13. The method of claim 11 further comprising repeating the supplying, using, forming, and treating process to further increase a thickness of the second thickness of material.

14. The method of claim 11 further comprising subjecting the cleaved surface region to a cleaning process.

15. The method of claim 14 wherein the cleaning process comprises exposure to a plasma.

16. The method of claim 14 wherein the cleaning process comprises exposure to a wet cleaning process.

17. A method of fabricating substrates for photovoltaic materials, the method comprising:

providing a donor substrate, the donor substrate including a cleave region, a surface region, and a first thickness of silicon or germanium material defined between the cleave region and the surface region;

transferring the first thickness of silicon or germanium material to a handle substrate surface region of a handle substrate to detach a portion of the donor substrate within a vicinity of the cleave region and to couple the surface region to the handle substrate surface region of the handle substrate to cause formation of a cleaved surface region overlying the first thickness of silicon or germanium material;

supplying a gas including a silane and/or germane species into a reaction chamber; and

depositing material, using a process selected from at least glow discharge, plasma, photo-enhanced or thermal CVD and the silane and/or germane species, overlying the cleaved surface to thicken the first thickness of silicon or germanium material at a deposition rate equal to or greater than or less than a solid phase epitaxial re-growth rate of the material to crystallize the material overlying the first thickness of silicon or germanium material.

18. The method of claim 17 wherein the depositing of the material occurs at a temperature of about 650 Degrees Celsius and less.

19. The method of claim 17 further comprising forming a seed layer by graphoepitaxy prior to depositing of the material.

20. The method of claim 17 wherein the silane species comprises tri-silane, di-silane, dichlorosilane, trichlorosilane, or monosilane.

21. The method of claim 17 wherein the germane species comprises germane (GeH4) or digermane (Ge2H6).

22. The method of claim 17 wherein the deposition of the silane and/or germane species includes one or more dopant gases to form P and N junction regions.

23. The method of claim 17 further comprising simultaneously depositing a second silicon material on a backside region of the handle substrate to form a first photovoltaic region on the handle substrate surface region and the backside of the handle substrate to respectively form a first photovoltaic material on the handle substrate surface region and a second photovoltaic material on the backside of the handle substrate.

24. A photovoltaic device comprising:

a handle substrate comprising a handle substrate surface region;

an interface material overlying the handle substrate surface region;

a layer transferred film overlying the interface material; and

a deposited thickness of single crystal silicon or single crystal germanium material having one or more defects therein.

25. The device of claim 24 wherein the deposited thickness of single crystal silicon or single crystal germanium has a P-type material overlying the layer transferred film and an N-type material overlying the P-type material.

26. The device of claim 25 wherein the P-type material comprises a P+ type material.

27. The device of claim 24 wherein the deposited thickness of single crystal silicon or single crystal germanium has an N-type material overlying the layer transferred film and a P-type material overlying the N-type material.

28. A method for fabricating a solar cell for use with one or more solar modules, the method comprising:

providing a support member having a surface region, a bottom portion, and a determined thickness between the surface region and the bottom portion;

forming a releasable material overlying the surface region of the support member;

transferring a first thickness of semiconductor material from a first donor substrate overlying the releasable material to form the first thickness of transferred material overlying the releasable material, the releasable material overlying the support member;

forming a second thickness of semiconductor material overlying the first thickness of transferred material to form a total thickness of material overlying the releasable material;

separating the total thickness of material from the releasable material to detach the total thickness of material from the releasable material; and

forming one or more photovoltaic devices onto one or more portions of the total thickness of material.

29. The method of claim 28 wherein the support member is characterized by a first coefficient of thermal expansion, the first coefficient of thermal expansion being substantially matched with a second coefficient of thermal expansion characterizing the first donor substrate.

30. The method of claim 28 wherein the surface region is characterized by a surface roughness and an overlying oxide layer.

31. The method of claim 30 wherein the surface roughness is provided by at least a porous material.

32. The method of claim 28 wherein the silicon support member comprises an opening region extending from the bottom portion of the support member, through the thickness of the support member, to a portion of the surface region, the opening region being coupled to a fluidic drive source, the fluidic drive source being capable of causing a pressure gradient within the opening region between the bottom portion and the portion of the surface region.

33. The method of claim 32 wherein the pressure gradient is provided by a fluid and facilitates removal of the total thickness from the releasable material.

34. The method of claim 33 wherein the fluid is an etchant to the releasable material.

35. The method of claim 28 wherein the cleaving comprises an initiating process for removing a portion of the total thickness from a portion of the releasable material and a propagation process for continuing the detachment of the total thickness from the releasable material.

36. The method of claim 28 wherein the forming the second thickness comprises depositing an epitaxial silicon material.

37. The method of claim 28 wherein the silicon support member is reusable.

38. The method of claim 28 wherein the releasable material comprises a surface roughness and an overlying dielectric material.

39. The method of claim 28 further comprising forming one or more photovoltaic devices onto one or more portions of the total thickness of material.

40. The method of claim 28 wherein the total thickness is characterized by a dimension of 200 microns and less.

41. A system for fabricating a solar cell, the system comprising:

a support member having a surface region, a bottom portion, and a determined thickness between the surface region and the bottom portion;

one or more openings provided in a spatial configuration on the surface region of the support member;

a fluidic source coupled to the one or more openings, the fluidic source being adapted to provide a fluid through the one or more openings on the surface region of the support member;

a releasable material overlying a surface region of the support member; and

a first thickness of semiconductor material overlying the releasable material to form the first thickness of transferred material overlying the releasable material, the releasable material overlying the support member.