Patent ID: 6951819

Claim:
A method of forming a multijunction solar cell comprising an upper subcell, a middle subcell, and at least one lower subcell, said method comprising: providing a growth semiconductor substrate for the epitaxial growth of semiconductor material; forming said upper subcell over said growth semiconductor substrate such that said upper subcell has a first upper band gap and is substantially lattice-matched to said growth substrate; forming said middle subcell over said upper subcell such that said middle subcell is substantially lattice-matched to said growth substrate and said middle subcell has a second middle band gap, said first upper band gap being larger than said second middle band gap; forming said at least one lower subcell over said middle subcell such that said at least one lower subcell is substantially lattice-mismatched with respect to said growth semiconductor substrate and said at least one lower subcell has a third lower band gap, said third lower band gap being smaller than said second middle band gap; providing a support structure over said lower subcell; and removing said growth semiconductor substrate.