Producing a ribbon or wafer with regions of low oxygen concentration

1. A method comprising:

providing a melt in a crucible, wherein the melt includes silicon;

forming a ribbon floating on the melt using a cold initializer facing an exposed surface of the melt, wherein the ribbon is single crystal silicon;

pulling the ribbon from the melt at a low angle off the melt surface, wherein the ribbon is formed at a same rate as the pulling; and

separating the ribbon from the melt at a wall of the crucible where a stable meniscus forms, wherein the ribbon has a thickness between a first surface and a second surface from 50 μm to 5 mm after the separating, wherein the second surface faces the melt prior to the separating, wherein the first surface and the second surface are opposite each other, wherein the ribbon includes a first region extending a first depth from the first surface toward the second surface, and wherein the first region has a reduced oxygen concentration relative to a bulk of the ribbon.

2. The method of claim 1 , wherein a speed of the pulling is from greater than 0.1 mm/s to 7 mm/s.

3. The method of claim 1 , wherein the crucible has a length in a direction of the forming from greater than 5 cm to 200 cm.

4. The method of claim 1 , wherein the ambient temperature around the ribbon is from 1200° C. to 1420° C. during the forming.

5. The method of claim 1 , wherein an atmosphere around the ribbon has a pressure from 0.01 atm to 5 atm during the forming.

6. The method of claim 1 , wherein an atmosphere around the crucible includes one or more of H 2 , Ar, He, another inert gas, or a combination thereof during the forming.

7. The method of claim 1 , wherein an atmosphere around the crucible during the forming includes oxygen and water vapor.

8. The method of claim 1 , wherein an atmosphere around the crucible during the forming includes phosphorous oxychloride or a chloride gas.

9. The method of claim 1 , wherein the pulling transports the ribbon through a plurality of gas zones after the separating, wherein each of the gas zones exposes the ribbon to a different gas.

10. The method of claim 1 , wherein the pulling transports the ribbon through a first zone and a second zone, wherein the first zone and the second zone operate at different temperatures, and wherein outgassing oxygen occurs in the first zone.

11. The method of claim 10 , wherein the first zone operates at from 1200° C. to 1400° C. and the second zone operates at less than 1200° C.

12. The method of claim 1 , further comprising outgassing oxygen from the first surface of the ribbon while the ribbon is in the melt during the pulling.

13. The method of claim 1 , further comprising outgassing oxygen from both the first surface and the second surface of the ribbon during the pulling after the separating.

14. The method of claim 1 , wherein an atmosphere around the crucible further includes a dopant during the forming.

15. The method of claim 1 , wherein the forming and pulling occur continuously to produce a ribbon from 0.2 m to 100 m in length.

16. The method of claim 1 , wherein the ribbon has a bulk minority carrier lifetime greater than 100 μs.

17. The method of claim 1 , further comprising supporting the ribbon during the pulling after the separating using gas flow levitation and/or a mechanical support, and wherein the supporting is configured to minimize contamination of the ribbon.

18. The method of claim 1 , further comprising melting a portion of the ribbon into the melt during the pulling.

19. The method of claim 1 , further comprising singulating the ribbon into one or more wafers.

20. A wafer produced using the method of claim 19 .

21. The wafer of claim 20 , wherein the wafer is a solar cell.

22. The wafer of claim 20 , wherein the wafer is a semiconductor wafer.

23. The wafer of claim 20 , wherein the wafer is a square, pseudo-square, rectangle, or circle.

24. The method of claim 1 , wherein the thickness between a first surface and a second surface is from 50 μm to 300 μm after the separating.

25. The method of claim 1 , wherein the first surface and the second surface are surfaces with a largest surface area on the ribbon.

26. The method of claim 1 , wherein the first region has an oxygen concentration from 0.1 to 8.0 ppma.

27. The method of claim 1 , wherein the bulk of the ribbon has an oxygen concentration from 8 to 25 ppma.

28. The method of claim 1 , wherein the first depth is at least 5 μm.

29. The method of claim 1 , wherein the first depth is from 5% to 90% of the thickness.

30. The method of claim 29 , wherein the first depth is from 20% to 90% of the thickness.

31. The method of claim 1 , wherein the first region has a reduced concentration of bulk micro defects relative to the bulk of the ribbon.

32. The method of claim 1 , further comprising a second region extending a second depth from the second surface toward the first surface, and wherein the second region has a reduced oxygen concentration relative to the bulk of the ribbon disposed between the first region and the second region.

33. The method of claim 32 , wherein the second region has an oxygen concentration from 0.1 to 8.0 ppma.

34. The method of claim 32 , wherein the second depth is at least 5 μm.

35. The method of claim 32 , wherein the first depth and the second depth combined is from 5% to 90% of the thickness.

36. The method of claim 32 , wherein the second depth is approximately 10% of the thickness.

37. The method of claim 32 , wherein the first region and the second region have a reduced concentration of bulk micro defects relative to the bulk of the ribbon disposed between the first region and the second region.

38. The method of claim 32 , wherein the first depth and the second depth are different distances.

39. The method of claim 1 , wherein the ribbon further includes a dopant.

40. The method of claim 1 , wherein the ribbon has an average oxygen precipitate count from 0 to 1e11/cm 3 in the first region.

41. A ribbon produced using the method of claim 1 .