Patent ID: 7919398

Claim:
A method of forming a thin film multi-junction solar cell over a substrate, comprising: forming a first p-i-n junction, comprising: forming a p-type amorphous silicon layer over the substrate; forming an intrinsic type amorphous silicon layer over the p-type amorphous silicon layer; and forming a first n-type silicon layer over the intrinsic type amorphous silicon layer; and forming a second p-i-n junction over the first p-i-n junction, comprising: forming a p-type microcrystalline silicon layer; forming an amorphous silicon barrier layer over the p-type microcrystalline silicon layer; forming an intrinsic type microcrystalline silicon layer over the amorphous silicon barrier layer, wherein forming the intrinsic type microcrystalline silicon layer comprises: forming a first region of the intrinsic type microcrystalline silicon layer at a first deposition rate; forming a second region of the intrinsic type microcrystalline silicon layer over the first region of the intrinsic type microcrystalline silicon layer at a second deposition rate higher than the first deposition rate; and forming a third region of the intrinsic type microcrystalline silicon layer over the second region of the intrinsic type microcrystalline silicon layer at a third deposition rate lower than the second deposition rate; and forming a second n-type silicon layer over the intrinsic type microcrystalline layer.