Patent ID: 7727795
Filing Date: 2010-06-01
Classification: H01L,Y02E,Y02P

Abstract:
1. A method of forming a multijunction solar cell comprising an upper subcell, a middle subcell, and a lower or bottom subcell, the method comprising: providing a first substrate for an epitaxial growth of a semiconductor material; forming a first solar subcell having a first base and a first emitter on said substrate, wherein said first solar subcell has a first band gap; forming a second solar subcell having a second base and a second emitter over said first solar subcell, wherein said second solar subcell has a second band gap smaller than said first band gap; forming a grading interlayer over said second solar subcell, said grading interlayer having a third band gap greater than said second band gap; and forming a third solar subcell having a third base and a third emitter over said grading interlayer, said third solar subcell having a fourth band gap smaller than said second band gap such that said third solar subcell is lattice mis-matched with respect to said second solar subcell, wherein at least one of the bases has an exponentially doped profile.