Manufacturing methods for semiconductor devices
View Patent ↗Embodiments of the present invention include a method. The method includes heating a layer stack. The layer stack includes a first layer comprising cadmium and tin, a metal layer disposed over the first layer, and a window layer disposed over the metal layer. Heating the stack includes transforming at least a portion of the first layer from an amorphous phase to a crystalline phase. Heating may be performed using any of various configurations, such as, for example, heating an individual stack, or using a face-to-face configuration of multiple stacks. The stack may be used for fabricating a photovoltaic device.
1. A method comprising:
heating a layer stack comprising a plurality of layers, the plurality of layers comprising
a) a first layer comprising cadmium and tin,
b) a metal layer capable of forming metal oxides and consisting essentially of metals having a higher affinity for oxygen than cadmium tin oxide, and
c) a window layer disposed over the metal layer;
wherein heating comprises transforming at least a portion of the first layer from an amorphous phase to a crystalline phase; and
wherein the plurality of layers further comprises an electrically resistive buffer layer disposed between the metal layer and the window layer.
2. The method of claim 1 , wherein the metal layer is disposed over the first layer.
3. The method of claim 1 , wherein the window layer comprises cadmium.
4. The method of claim 3 , wherein the window layer comprises cadmium sulfide.
5. The method of claim 1 , wherein the buffer layer comprises tin oxide, zinc oxide, zinc tin oxide, zinc stannate, zinc magnesium oxide, gallium oxide, aluminum oxide, or silicon oxide.
6. The method of claim 1 , wherein the crystalline phase comprises a spinel.
7. The method of claim 6 , wherein the spinel comprises cadmium, tin, and oxygen.
8. The method of claim 1 , wherein heating comprises heating the first layer to a temperature in a temperature range from about 500° C. to about 700° C.
9. The method of claim 1 , wherein heating comprises holding the first layer at said temperature range for a hold time in the range up to about 60 minutes.
10. The method of claim 1 , wherein the metal layer is selected from layers of tin, aluminum, zinc, tantalum, titanium, zirconium, vanadium, indium, nickel, or magnesium.
11. The method of claim 1 , wherein the metal layer has a thickness up to about 30 nanometers.
12. The method of claim 1 , wherein the metal layer has a thickness in a range from about 1 nanometer to about 20 nanometers.
13. The method of claim 1 , wherein the plurality of layers further comprises an absorber layer disposed over the window layer.
14. The method of claim 13 , wherein the absorber layer comprises cadmium telluride.
15. The method of claim 1 , wherein heating the layer stack comprises heating the layer stack disposed on a support.
16. The method of claim 15 , wherein the support comprises a glass.
17. The method of claim 15 , wherein the support comprises a metal or a polymer.
18. The method of claim 1 , wherein heating comprises heating the stack in the presence of a cadmium-containing material disposed external to the stack.
19. The method of claim 1 , wherein heating further comprises heating an assembly, the assembly comprising a first panel comprising a first layer stack disposed on a first support, and a second panel comprising a second layer stack disposed on a second support,
wherein the window layer of the second panel faces the window layer of the first panel.
20. A method comprising:
heating an assembly, the assembly comprising a first panel comprising a first layer stack disposed on a first support, and a second panel comprising a second layer stack disposed on a second support,
wherein each of the first layer stack and the second layer stack comprises
a) a first layer comprising cadmium and tin,
b) a metal layer disposed over the first layer, the metal layer capable of forming metal oxides and consisting essentially of metals having a higher affinity for oxygen than cadmium tin oxide, and
c) a window layer disposed over the metal layer;
wherein the window layer of the second panel faces the window layer of the first panel, and
wherein heating comprises transforming at least a portion of the first layer of either layer stack, or of both layer stacks, from an amorphous phase to a crystalline phase.
21. The method of claim 20 , wherein the window layers comprise cadmium, such that the window layer of the second layer stack provides a cadmium-containing material disposed external to the first stack and the window layer of the first layer stack provides a cadmium-containing material disposed external to the second stack.
22. A method comprising:
heating a layer stack comprising a plurality of layers, the plurality of layers comprising
a) a first layer comprising cadmium and tin,
b) a metal layer, the metal layer capable of forming metal oxides and consisting essentially of metals having a higher affinity for oxygen than cadmium tin oxide, and
c) a window layer disposed over the metal layer;
wherein heating comprises transforming at least a portion of the first layer from an amorphous phase to a crystalline phase; and wherein heating further comprises heating the stack in the presence of a cadmium-containing material disposed external to the stack, the cadmium-containing material comprising cadmium sulfide or cadmium oxide.