1. Substitute beer and pizza?

2. Basic Silicon Solar Cell as fabricated in Cameron With Schematic

3. A detailed traveler is used to define the process steps

4. The process begins with a silicon wafer, 100mm in diameter, (100) orientation, PRIME grade, p-type boron doped, 1-10 ohm-cm resistivity

5. The process begins with a silicon wafer, 100mm diameter, (100) orientation, PRIME grade, p-type boron doped, 1-10 ohm-cm resistivity Shown in cross section of wafer

6. The wafer is cleaned using the sulfuric acid/hydrogen peroxide clean

7. Using PECVD (plasma enhanced chemical vapor deposition) the back side is coated with SiO2 to prevent doping of the backside

8. Using POCl 3 as the source for phosphorus doping an n-region will be created in the p- type silicon wafer POCl 3 bubbler – nitrogen is bubbled through the liquid POCl 3 and carries phosphorus into the tube

9. With the POCl 3 running into the tube, phophorus is diffused into the silicon wafer at 950C

10. A n-region is now diffused into the silicon wafer at 950C

11. A metal film (aluminum) is sputtered on the top surface and a photolithographic mask creates a conductive grid in the metal

12. A metal film (Aluminum) is sputtered on the top surface and a photolithographic mask creates a conductive grid in the metal

13. Positive photoresist is spun on the metal coated wafer

14. A transparency mask of the top side grid is placed on top of the photoresist coated wafer and exposed to UV

15. The image is developed which leaves the metal conductor pattern

16. With photoresist protecting the metal, the unprotected metal is etched away leaving the top side grid pattern in metal

17. A metal film is evaporated on the top surface and a photolithographic mask creates a conductive grid in the metal

18. A second metal film (aluminum) is deposited on the back for backside contact

19. A second metal film is deposited on the back for backside contact

20. Using PECVD (plasma enhanced chemical vapor deposition) an anti-reflective coating of SiO2 is deposited on the top surface

21. Using PECVD (plasma enhanced chemical vapor deposition) a anti-relective coating of SiO2 is deposited on the top surface

22. Individual cells are diamond saw cut from the wafer

24. Electrical testing (I-V trace) of the cell is performed under a solar light simulator Calibration cell determines the intensity of sunlight

25. Electrical testing (I-V trace) of the cell is performed under a solar light simulator

26. Blue trace is without sun light, red trace is with sunlight at 1.0 sun

27. Completed Solar Cell

28. Assignment Lecture 4 assignment from web site