Patent ID: 8236600

Claim:
A method of manufacturing a solar cell comprising: providing a first semiconductor substrate; depositing on the first semiconductor substrate a first sequence of layers of semiconductor material to form a first subassembly comprising an upper first solar subcell on said first semiconductor substrate, a middle second solar subcell over said upper first solar subcell, a graded interlayer over said middle second solar subcell, and a lower third solar subcell over said graded interlayer including a first lattice matched semiconductor layer disposed on a top surface of said first sequence of layers, wherein said first lattice matched semiconductor layer includes InGaAs; providing a second semiconductor substrate, wherein the second semiconductor substrate comprises germanium; depositing on a top surface of the second semiconductor substrate a second sequence of layers of semiconductor material forming a second subassembly comprising at least a third subcell including a second lattice matched semiconductor layer disposed on a top surface of said second sequence of layers; joining the first subassembly and the second subassembly by positioning the first lattice matched semiconductor layer of the first subassembly adjacent to the second lattice matched semiconductor layer of the second subassembly to form a bond joining the first and second assemblies, thus forming a multijunction device; and removing the first semiconductor substrate to expose an uppermost subcell of the multijunction device.