Method and apparatus providing single step vapor chloride treatment and photovoltaic modules

Patent metadata

Field	Value
Publication number	US-9318642-B2
Application number	US-201213678800-A
Country	US
Kind code	B2
Filing date	Nov 16, 2012
Priority date	Nov 18, 2011
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A method and apparatus are disclosed in which cadmium chloride is deposited on a cadmium telluride layer while simultaneously heat treating the cadmium telluride layer.

First claim

What is claimed as new and desired to be protected by Letters Patent of the United States is:

1. A method of treating a cadmium telluride layer, the method comprising:
forming a cadmium chloride vapor from powdered cadmium chloride in a vaporization unit;
moving a substrate containing a cadmium telluride layer through a controlled ambient deposition oven;
continuously depositing the cadmium chloride vapor from the vaporization unit on the cadmium telluride layer in the controlled ambient oven as the substrate moves through the oven; and
heat treating the cadmium telluride layer at a temperature to heat treat and crystallize the cadmium telluride layer, wherein the steps of depositing the cadmium chloride vapor and heat treating the cadmium telluride layer occur simultaneously to provide a continuous single step of cadmium chloride deposition and heat treatment of the cadmium telluride layer, the continuous single step deposition of the cadmium chloride and heat treating the cadmium telluride layer occurring in the oven; and
forming a back contact metal on the single step cadmium chloride deposited and heat treated cadmium telluride layer.

2. The method of claim 1 , further comprising transporting the substrate through the oven at the same time as depositing the cadmium chloride and heat treating the cadmium telluride layer.

3. The method of claim 1 , further comprising vaporizing the cadmium chloride powder in the vaporizer unit at a vaporizing temperature that is higher than a temperature at which the cadmium telluride layer is heat treated.

4. The method of claim 3 , wherein the temperature at which the cadmium telluride layer is heat treated is about 385 to about 500 degrees Celsius.

5. The method of claim 3 , wherein the temperature at which the cadmium telluride layer is heat treated is about 400 to about 450 degrees Celsius.

6. The method of claim 1 , further comprising depositing the cadmium chloride vapor on the cadmium telluride layer using a diffuser.

7. The method of claim 6 , further comprising using a carrier gas to distribute the vaporized cadmium chloride.

8. An apparatus for manufacturing a photovoltaic module, comprising:
a controlled ambient oven comprising a heater for heating the interior of the oven, the oven having associated structures to control internal oxygen levels within the oven;
a vaporization unit arranged outside the oven for vaporizing powdered cadmium chloride;
a conveyor for continuously moving a substrate containing a cadmium telluride layer through the oven;
a diffuser arranged inside the oven for continuously diffusing vaporized cadmium chloride from the vaporization unit within the oven onto the cadmium telluride material as the substrate moves though the oven, wherein the vaporization unit and heater operate to deposit the cadmium chloride on the cadmium telluride material and simultaneously heat treat the cadmium chloride coated cadmium telluride material to heat treat the coated cadmium telluride material to increase grain size and to thereby provide a continuous single step deposition of the cadmium chloride and heat treatment of the cadmium telluride material.

9. The apparatus of claim 8 , further comprising a transport mechanism arranged inside the oven for transporting a substrate through the oven.

10. The apparatus of claim 9 , wherein the transport mechanism comprises a belt or a plurality of rollers.

11. The apparatus of claim 8 , wherein the temperature of the vaporization unit and the temperature of the heater are controlled separately.

12. The apparatus of claim 8 , wherein the oven comprises loading/exit locks or gas curtains to control internal oxygen levels of the oven.

13. An apparatus for manufacturing a photovoltaic module, comprising:
a controlled ambient oven comprising a heater for heat treating a cadmium telluride layer arranged on a substrate;
a vaporization unit for vaporizing powdered cadmium chloride;
a conveyor for continuously moving the substrate and cadmium telluride layer through the oven;
a diffuser arranged inside the oven for continuously diffusing vaporized cadmium chloride from the vaporization unit within the oven and depositing cadmium chloride vapor into the cadmium telluride layer as the substrate moves through the oven, wherein depositing the cadmium chloride occurs within the oven at the same time as heat treating the cadmium telluride layer to provide a continuous single step deposition of the cadmium chloride and heat treatment of the cadmium telluride layer within the oven,
wherein the vaporization unit is an ex-situ vaporization unit arranged outside the oven.

Assignees

• First Solar Inc

Inventors

• Gupta Akhlesh
• Gloeckler Markus
• Powell Ricky C

Classifications

• H10P72/3202

  Mechanical details, e.g. rollers or belts · CPC title

• H10P72/0466

  characterised by the construction of the load-lock chamber · CPC title

• H10P72/0434

  mainly by convection · CPC title

• H10P14/3432 Primary

  Tellurides · CPC title

• H10P14/38

  characterised by treatments done after the formation of the materials · CPC title