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Thermal Sprayed Silicon Microstructure
- 1. Microstructure of thermal sprayed silicon coatings using various particle sizes and spray conditions Damon D Jackson, Mike Sereda, Bob Nafzinger Senergen Devices, Fremont, CA Robert Gansert Advanced Materials & Technology Services, Inc., Simi Valley CA
- 3. Semiconductor on a Roof p-n junction absorbs light and separates charges
- 4. Semiconductor on a Roof Add contacts on the wafer to make a solar cell
- 5. Semiconductor on a Roof Connect solar cells to make a module
- 6. Semiconductor on a Roof Modules on a roof generate electricity
- 7. PV Silicon • 150-200 microns thick wafer • Low impurity silicon • 15-22% energy conversion efficiencies • 40-50% material losses during cutting
- 8. PV Silicon • 150-200 microns thick wafer • Low impurity silicon • 15-22% energy conversion efficiencies • 40-50% material
- 9. PV Thin-Film Silicon Solar • 25-50 microns thick • 10-17% efficiencies • Less importance on Si impurities • Small thickness allows for small carrier lifetimes
- 10. Concerns for PV • Porosity and voids • Highly poly • Impurities • Initial powder • Introduced through equipment (ie: Cu from anode)
- 11. Early use in PV Abstract A method for producing a semiconductor solar cell in which a layer of semiconductor material is applied to a substrate by means of plasma spraying. The energy density in the plasma zone is maintained sufficiently high that the semiconductor vaporizes and is brought out of the plasma zone in the form of a vapor jet, which is condensed on the substrate in the form of a semiconductor layer. USPTO 4,449,286 (1984)
- 12. Examples Today • Integrated Photovoltaics is working on a custom built, silicon coated gun • Also have a process for making pure powder • Claim they can make semiconductor grade silicon coatings USPTO, filed 2008
- 13. Senergen Devices • Thermal spray for inexpensive base layer • Heat treatment to Thermal spray - MG-Si 0.15 mm reduce porosity • Deposit high purity active layer using RF Plasma
- 14. Senergen Devices • Thermal spray for inexpensive base layer • Heat treatment to Thermal spray - MG-Si 0.15 mm reduce porosity • Deposit high purity active layer using RF Plasma
- 15. Senergen Devices • Thermal spray for inexpensive base layer High purity Si 0.05 mm • Heat treatment to Thermal spray - MG-Si 0.15 mm reduce porosity • Deposit high purity active layer using RF Plasma
- 16. Senergen Devices • Thermal spray for inexpensive base layer High purity Si 0.05 mm • Heat treatment to Thermal spray - MG-Si 0.15 mm reduce porosity • Deposit high purity active layer using RF End with 200 micron Plasma wafer-equivalent
- 18. Process Depends on Powders • Powder ʻAʼ • 34 µm, large distribution • Powder ʻBʼ • 28 µm, tight distribution • Powder ʻCʼ • 74 µm, medium distribution
- 19. Powder ʻAʼ • Vary the spray distance • Dwell time in plasma
- 20. Powder ʻAʼ 2 inches • Vary the spray distance • Dwell time in plasma
- 21. Powder ʻAʼ 3 inches • Vary the spray distance • Dwell time in plasma
- 22. Powder ʻAʼ 4 inches • Vary the spray distance • Dwell time in plasma
- 23. Powder ʻBʼ • Vary the plasma current (2”) • Increase enthalpy
- 24. Powder ʻBʼ 400 A • Vary the plasma current (2”) • Increase enthalpy
- 25. Powder ʻBʼ 450 A • Vary the plasma current (2”) • Increase enthalpy
- 26. Powder ʻBʼ 500 A • Vary the plasma current (2”) • Increase enthalpy
- 27. Powder ʻCʼ • Vary the plasma current (6”) • Increase enthalpy
- 28. Powder ʻCʼ 400 A • Vary the plasma current (6”) • Increase enthalpy
- 29. Powder ʻCʼ 600 A • Vary the plasma current (6”) • Increase enthalpy
- 30. Powder ʻCʼ 800 A • Vary the plasma current (6”) • Increase enthalpy
- 31. Identifying Best Parameters • Small Particle sizes • easier to melt • oxidization • Larger Particle sizes • higher power required • lower porosity
- 32. Senergen Thermal Spray Process • Senergen used results such as this to make free standing silicon substrates • Film quality important for PV • Improvements in DE determine costs