TARGET MATERIALS FOR FABRICATING SOLAR CELLS
A sputtering target device is provided for manufacturing solar cells. The target device includes a metal selected from a group consisting of copper, indium, and molybdenum and further includes antimony or antimony-containing compound mixed in a matrix of the metal. The target device comprises antimony of 0.1 to 20 wt % and the metal of at least 80 wt %. The target device is installed in a deposition system for forming a back electrode doped with antimony or for forming at least one precursor layer doped with antimony among a stack of multiple precursor layers for forming a semiconductor photovoltaic absorber material.
1 . A sputtering target device for manufacturing solar cells comprising:
metal from a group consisting of copper, indium, and molybdenum; and
antimony or an antimony-containing compound mixed in a matrix of the metal, wherein said target device comprises antimony of 0.1 and 20 wt % and the metal of at least 80 wt %.
2 . The sputtering target device of claim 1 wherein said target device comprises antimony of 0.5 to 9.0 wt % and copper of 91.0 to 99.5 wt %.
3 . The sputtering target device of claim 1 wherein said target device comprises antimony of 1.0 to 10 wt % and indium of 90.0 to 99.0 wt %.
4 . The sputtering target device of claim 1 wherein said target device comprises antimony of 1.0 to 10 wt % and molybdenum of 90.0 to 99.0 wt %.
5 . The sputtering target device of claim 1 wherein said target device comprises a bulk shaped material formed by sintering a powder mixture of the metal and the antimony-containing compound in a target support, the bulk shaped material being characterized by a shape selected from rectangle, disk, cylinder, hollowed cylinder, semi-hollowed cylinder, ring, square, and triangle.
6 . A sputtering target device comprising:
at least a metal selected from copper, indium, and molybdenum;
a sodium sulfide compound; and
an antimony or an antimony-containing compound mixed in a matrix of the at least the metal with the sodium sulfide compound, wherein said target device comprises antimony of 0.1 to 15 wt %, sodium sulfide of 0.1 to 5 wt %, and the at least the metal of at least 80 wt %.
7 . The target device of claim 6 wherein said target device comprises antimony of 0.5 to 9.0 wt %, sodium sulfide of 0.1 to 5.0 wt %, and copper of at least 86 wt %.
8 . The target device of claim 6 wherein said target device comprises antimony of 0.5 to 9.0 wt %, sodium sulfide of 0.1 to 5.0 wt %, and indium of at least 86 wt %.
9 . The target device of claim 6 wherein said target device comprises antimony of 0.5 to 9.0 wt %, sodium sulfide of 0.1 to 5.0 wt %, and molybdenum of at least 86 wt %.
10 . A method of making solar cells comprising:
providing a substrate;
forming a back electrode layer overlying the substrate, wherein the back electrode layer is a molybdenum-antimony alloy grown from a sputtering target comprising antimony of 0.1 to 15.0 wt % and molybdenum of at least 85 wt %;
forming a stack of multiple precursor layers overlying the back electrode layer, wherein the stack of multiple precursor layers comprises a first thickness of copper layer, a second thickness of indium layer, a third thickness of copper layer, a fourth thickness of gallium layer, and a fifth thickness of selenium layer;
subjecting the stack of multiple precursor layers to a thermal annealing process at a temperature between 450 and 600 Degrees Celsius for about 10 minutes to form an absorber material having antimony as a dopant;
forming an n-type semiconductor comprising cadmium sulfide overlying the absorber material;
forming a zinc oxide layer overlying the n-type semiconductor followed by forming an aluminum doped zinc oxide layer over the zinc oxide layer; and
forming a front electrode overlying the aluminum doped zinc oxide layer.
11 . The method of claim 10 wherein the absorber material comprises a copper-indium-gallium-selenide compound having a chemical stoichiometry of determined by the first thickness, the second thickness, the third thickness, the fourth thickness, and the fifth thickness of corresponding precursor layers, the copper-indium-gallium-selenide compound comprising antimony doped via the back electrode layer.
12 . The method of claim 10 wherein the chemical stoichiometry comprises a first ratio of copper/(indium+gallium) in a range of 0.75 to 0.95, a second ratio of gallium/(indium+gallium) in a range of 0.25 to 0.5, and a third ratio of selenium/(copper+indium+gallium) about 1.0.
13 . A method of making solar cells comprising:
providing a substrate;
forming a molybdenum layer as a back electrode overlying the substrate;
forming a stack of multiple precursor layers comprising copper, indium, gallium, and selenium sequentially overlying the back electrode, wherein one of the multiple precursor layers is formed by sputtering from a target device comprising 0.1 to 20 wt % of antimony and at least 80 wt % of a metal element selected from a group of metal materials consisting of copper, indium, and gallium;
subjecting the substrate including the molybdenum layer and the stack of multiple precursor layers to a thermal annealing process at a temperature between 450 and 600 Degrees Celsius for about 10 minutes to form an absorber material having at least antimony as a dopant;
forming an n-type semiconductor comprising cadmium sulfide overlying the absorber material;
forming a zinc oxide layer overlying the n-type semiconductor followed by forming an aluminum doped zinc oxide layer over the zinc oxide layer; and
forming a front electrode overlying the aluminum doped zinc oxide layer.
14 . The method of claim 13 wherein the stack of multiple precursor layers comprises:
a first thickness of copper-antimony layer formed from sputtering a target device comprising antimony of 0.5 to 9.0 wt % and copper of at least 91 wt %;
a second thickness of indium layer;
a third thickness of copper layer;
a fourth thickness of gallium layer; and
a fifth thickness of selenium layer.
15 . The method of claim 13 wherein the stack of multiple precursor layers comprises:
a first thickness of copper layer;
a second thickness of indium-antimony layer formed from sputtering a target device comprising antimony of 0.5 to 9.0 wt % and indium of at least 91 wt %;
a third thickness of copper layer;
a fourth thickness of gallium layer; and
a fifth thickness of selenium layer.
16 . The method of claim 13 wherein the stack of multiple precursor layers comprises:
a first thickness of copper layer;
a second thickness of indium layer;
a third thickness of copper-antimony layer formed from sputtering a target device comprising antimony of 0.5 to 9.0 wt % and copper of at least 91 wt %;
a fourth thickness of gallium layer; and
a fifth thickness of selenium layer.
17 . The method of claim 13 wherein the stack of multiple precursor layers comprises:
a first thickness of copper layer;
a second thickness of gallium layer;
a third thickness of copper layer;
a fourth thickness of indium-antimony layer formed from sputtering a target device comprising antimony of 0.5 to 9.0 wt % and indium of at least 91 wt %; and
a fifth thickness of selenium layer.
18 . The method of claim 13 wherein the stack of multiple precursor layers comprises:
a first thickness of copper layer;
a second thickness of gallium layer;
a third thickness of copper-antimony layer formed from sputtering a target device comprising antimony of 0.5 to 9.0 wt % and copper of at least 91 wt %;
a fourth thickness of indium layer; and
a fifth thickness of selenium layer.
19 . The method of claim 13 wherein the absorber material comprises a copper-indium-gallium-selenide compound having a chemical stoichiometry of determined by corresponding thicknesses of the multiple precursor layers including at least one layer doped by antimony.
20 . The method of claim 19 wherein the chemical stoichiometry comprises a first ratio of copper/(indium+gallium) in a range of 0.75 to 0.95, a second ratio of gallium/(indium+gallium) in a range of 0.25 to 0.5, and a third ratio of selenium/(copper+indium+gallium) about 1.0.