Real time process monitoring and control for semiconductor junctions
A method of manufacturing a semiconductor layer is provided. In a first deposition during a first period of time, at least one Group IIIA element and at least one Group VIA element are deposited on a substrate or on a layer optional disposed on the substrate such as a back-electrode. During a second deposition during a second period of time, at least one Group IB element and the at least one group VIA element are deposited on the substrate or the optional layer. The one Group IB element combines with the Group VIA element to form a IB 2 VIA composition. A first deposition state is monitored, during the second deposition by making a first plurality of measurements of a first deposition state. The second deposition is terminated or attenuated based on a function of the first plurality of measurements of the indicia of the first deposition state.
1. A photovoltaic module comprising:
a substrate; and
a plurality of solar cells linearly arranged on said substrate, the plurality of solar cells comprising a first solar cell and a second solar cell, each solar cell in said plurality of solar cells comprising:
a back-electrode disposed on said substrate;
a semiconductor junction disposed on said back-electrode; and
a transparent conductive layer disposed on said semiconductor junction, wherein
the transparent conductive layer of the first solar cell in said plurality of solar cells is in serial electrical communication with the back-electrode of the second solar cell in said plurality of solar cells, and wherein a layer of said semiconductor junction is constructed by:
i) depositing, during a first period of time, at least one Group IIIA element and at least one Group VIA element on said back-electrode;
ii) depositing, during a second period of time, at least one Group IB element and said at least one group VIA element, on the substrate or on the optional layer that is optionally disposed on the substrate, wherein at least a portion of said at least one Group IB element combines with said at least one Group VIA element to form a IB 2 VIA composition on said back-electrode;
iii) monitoring a first deposition state, during said depositing step ii), by making a first plurality of measurements of an indicia of said first deposition state; and
iv) terminating or attenuating said depositing step ii) at a first critical control point based on a function of said first plurality of measurements of said indicia of said first deposition state.
2. The photovoltaic module of claim 1 , wherein the layer of said semiconductor junction layer is further constructed by:
v) depositing, during a third period of time, at least one additional Group IIIA element and said at least one Group VIA element;
vi) monitoring a second deposition state, during said depositing step v), by making a second plurality of measurements of an indicia of said second deposition state; and
vii) terminating or attenuating said depositing step v) at a second critical control point based on a function of said second plurality of measurements of said indicia of said second deposition state.
3. The photovoltaic module of claim 1 , wherein said at least one Group IIIA element comprises Gallium (Ga), Indium (In), Aluminum (Al), or Thallium (Tl).
4. The photovoltaic module of claim 1 , wherein said at least one Group VIA element comprises Sulfur (S), Selenium (Se), Tellurium (Te), or Polonium (Po).
5. The photovoltaic module of claim 1 , wherein said at least one Group IB element comprises Copper (Cu), Silver (Ag), or Gold (Au).
6. The photovoltaic module of claim 1 , wherein said semiconductor layer comprises CuIn 1-x Ga x Se 2 , 0≦x≦1.
7. The photovoltaic module of claim 1 , wherein said semiconductor layer comprises CuIn 1-x Ga x (Se y S 1-y ) 2 , where 0≦x, y≦1.
8. The photovoltaic module of claim 1 , wherein said substrate is cylindrical.
9. The photovoltaic module of claim 1 , wherein said substrate is planar.
10. The photovoltaic module of claim 1 , wherein said first period of time is between 15 minutes and 60 minutes.
11. The photovoltaic module of claim 1 , wherein said second period of time is between 15 minutes and 60 minutes.
12. The photovoltaic module of claim 2 , wherein said third period of time is between 15 minutes and 60 minutes.
13. The photovoltaic module of claim 1 , wherein there is a time gap between said depositing step i) and depositing step ii).
14. The photovoltaic module of claim 13 , wherein a precursor is formed on said substrate or said optional layer on said substrate during at least a portion of said time gap.
15. The photovoltaic module of claim 13 , wherein a precursor is formed by said at least one Group IIIA element and said at least one Group VIA element during at least a portion of said time gap.
16. The photovoltaic module of claim 1 , wherein said function of said first plurality of measurements of said indicia of said first deposition state is a second order derivative, with respect to time, of said first plurality of measurements.
17. The photovoltaic module of claim 16 , wherein said first critical control point occurs when said second order derivative, with respect to time, approaches a threshold value.
18. The photovoltaic module of claim 17 , wherein said threshold value is zero.
19. The photovoltaic module of claim 2 , wherein said function of said second plurality of measurements of said indicia of said second deposition state is a second order derivative, with respect to time, of said second plurality of measurements.
20. The photovoltaic module of claim 19 , wherein said second critical control point occurs when said second order derivative, with respect to time, approaches a threshold value.
21. The photovoltaic module of claim 20 , wherein said threshold value is zero.
22. The photovoltaic module of claim 1 , wherein said IB 2 VIA composition is Cu 2 Se.
23. The photovoltaic module of claim 1 , wherein said indicia of said first deposition state is a temperature of said substrate or said optional layer on said substrate, a refractive index of said substrate or said optional layer on said substrate, or a vapor pressure.
24. The photovoltaic module of claim 2 , wherein said indicia of said second deposition state is a temperature of said substrate or said optional layer on said substrate, a refractive index of said substrate or said optional layer on said substrate, or a vapor pressure.
25. The photovoltaic module of claim 2 , wherein said indicia of said first deposition state and said indicia of said second deposition state are the same.
26. The photovoltaic module of claim 2 , wherein said indicia of said first deposition state and said indicia of said second deposition state are different.
27. The photovoltaic module of claim 1 , wherein said function of said first plurality of measurements of said indicia of said first deposition state is a first order derivative, with respect to time, of said first plurality of measurements of said indicia of said first deposition state.
28. The photovoltaic module of claim 27 , wherein said first critical control point occurs when said first order derivative, with respect to time, falls below a threshold value.
29. The photovoltaic module of claim 28 , wherein the first order derivative, with respect to time, falls below said threshold value when said first order derivative achieves a minimum value.
30. The photovoltaic module of claim 27 , wherein said first critical control point occurs when said first order derivative, with respect to time, rises above a threshold value.
31. The photovoltaic module of claim 30 , wherein the first order derivative, with respect to time, rises above said threshold value when said first order derivative achieves a maximum value.
32. The photovoltaic module of claim 2 , wherein said function of said second plurality of measurements of said indicia of said second deposition state is a first order derivative, with respect to time, of said second plurality of measurements of said indicia of said second deposition state.
33. The photovoltaic module of claim 32 , wherein said second critical control point occurs when said first order derivative, with respect to time, falls below a threshold value.
34. The photovoltaic module of claim 33 , wherein the first order derivative, with respect to time, falls below said threshold value when said first order derivative achieves a minimum value.
35. The photovoltaic module of claim 32 , wherein said second critical control point occurs when said first order derivative, with respect to time, rises above a threshold value.
36. The photovoltaic module of claim 35 , wherein the first order derivative, with respect to time, rises above said threshold value when said first order derivative, with respect to time, achieves a maximum value.
37. The photovoltaic module of claim 1 , wherein said at least one Group IIIA element and said at least one Group VIA element form a precursor IIIA 2 VIA 3 composition on said substrate or said optional layer on said substrate.
38. The photovoltaic module of claim 37 , wherein said precursor IIIA 2 VIA 3 composition is (In x Ga 1-x ) 2 (Se y S 1-y ) 3 , where 0≦x, and y≦1.
39. The photovoltaic module of claim 37 , wherein said precursor IIIA 2 VIA 3 composition is (In x Ga 1-x ) 2 Se 3 , where 0≦x≦1.
40. The photovoltaic module of claim 1 , wherein the optional layer is disposed on the substrate.
41. The photovoltaic module of claim 40 , wherein the optional layer is a back-electrode.
42. The photovoltaic module of claim 1 , wherein the optional layer is not disposed on the substrate and the i) depositing step i) deposits at least one Group IIIA element and at least one Group VIA element on the substrate.