TECHNIQUE FOR DOPING COMPOUND LAYERS USED IN SOLAR CELL FABRICATION
The present invention includes methods and apparatus therefrom for preparing thin films of doped semiconductors for radiation detector and photovoltaic applications, and particularly method and apparatus that increase dopants of alkali metals in Group IBIIIAVIA layers. In a particular aspect, the present invention includes a method of preparing a doped Group IBIIIAVIA absorber layer for a solar cell, with the absorber layer being formed by reaction, with a Group VIA material, of a metallic stack with a plurality of layers, in which each layer contains a concentration of an alkali metal selected from the group of Na, K and Li.
1 . A method of preparing a doped Group IBIIIAVIA absorber layer for a solar cell, the method comprising:
forming a metallic stack, the step of forming the metallic stack including the steps of:
electroplating at least one layer of a Group IB material using one or more Group IB plating solutions, and
electrodepositing at least one layer of a Group IIIA material using one or more Group IIIA plating solutions; and
reacting the metallic stack with at least one Group VIA material,
wherein the one or more Group IB plating solutions and the one or more Group IIIA plating solutions each contain a concentration of an alkali metal selected from the group of Na, K and Li.
2 . The method according to claim 1 wherein the Group IB material is Cu, at least one layer of the Group IIIA material is a plurality of layers including an In layer and a Ga layer.
3 . The method according to claim 2 wherein the steps of electroplating and electrodepositing form a metallic stack selected from the group of Cu/Ga/In, Cu/Ga/Cu/In, Ga/Cu/In, In/Cu/Ga, Cu/In/Ga, In/Cu/Ga/Cu, In/Cu/Ga/In, In/Cu/In/Ga, In/Cu/Ga/In/Cu, In/Cu/In/Ga/Cu, Ga/Cu/In/Cu, Ga/Cu/In/Ga, Ga/Cu/Ga/In, Ga/Cu/In/Ga/Cu, Ga/Cu/Ga/In/Cu, Ga/In/Cu, Ga/In/Cu/Ga, Ga/In/Cu/In, Ga/In/Cu/Ga/Cu, Ga/In/Cu/In/Cu, Ga/In/Ga/Cu, In/Ga/Cu, In/Ga/Cu/In, In/Ga/Cu/Ga/Cu, and In/Ga/Cu/In/Cu.
4 . The method according to claim 3 wherein the concentration of the alkali metal is in the range of 500 ppm-2M.
5 . The method according to claim 1 further comprising a step of electrodepositing a layer of Se using a Se plating solution on the metallic stack thus forming a precursor layer.
6 . The method according to claim 5 wherein the Se plating solution comprises an amount of an alkali metal selected from the group of Na, K and Li.
7 . The method according to claim 6 wherein the amount of the alkali metal is in the range of 500 ppm-2M.
8 . The method according to claim 1 wherein the metallic stack contains at least 10 19 atoms/cc of the alkali metal.
9 . The method according to claim 6 wherein the precursor layer contains at least 10 19 atoms/cc of the alkali metal.
10 . A method of preparing a doped Group IBIIIAVIA absorber layer for a solar cell, the method comprising:
forming a metallic stack, the step of forming the metallic stack including the steps of:
electroplating at least one metallic layer including Cu and at least one of Ga and In using a first plating solution, and
electrodepositing at least one film including at least one of Ga and In using a second plating solution; and
reacting the metallic stack with at least one Group VIA material,
wherein the first plating solution and the second plating solution each contains a concentration of an alkali metal selected from the group of Na, K and Li.
11 . The method according to claim 10 wherein the concentration of the alkali metal is in the range of 500 ppm-2M.
12 . The method according to claim 10 further comprising a step of electrodepositing a layer of Se using a Se plating solution on the metallic stack thus forming a precursor layer.
13 . The method according to claim 12 wherein the Se plating solution includes an amount of an alkali metal selected from the group of Na, K and Li.
14 . The method according to claim 13 wherein the amount of the alkali metal is in the range of 500 ppm-2M.
15 . The method according to claim 13 wherein the precursor layer contains at least 10 19 atoms/cc of the alkali metal.
16 . The method according to claim 10 wherein the metallic stack contains at least 10 19 atoms/cc of the alkali metal.