Exponentially Doped Layers In Inverted Metamorphic Multijunction Solar Cells

A multifunction solar cell comprising an upper subcell, a middle subcell, and a lower or bottom subcell, comprising:

• a first solar subcell having a base and an emitter having a first band gap;
• a second solar subcell having a base and an emitter disposed over said first solar subcell having a second band gap smaller than said first band gap;
• a grading interlayer disposed over said second solar subcell, said grading interlayer having a third band gap greater than said second band gap;
• and
• a third solar subcell having a base and an emitter disposed over said grading interlayer having a fourth band gap smaller than said second band gap such that said third subcell is lattice mismatched with respect to said second subcell,
• wherein at least one of the bases has an exponentially doped profile.

A semiconductor structure for use in manufacturing a solar cell comprising:

• a first substrate;
• a sequence of layers of semiconductor material forming a solar cell including at least one base layer with exponential doping;
• mounting a surrogate substrate on top of the sequence of layers disposed on said first substrate;
• and
• a surrogate substrate mounted on top of the sequence of layers.

A solar cell comprising:

• a top cell including base and emitter layers composed of InGaP semiconductor material;
• a middle cell emitter layer of GaAs semiconductor material and a base layer of InGaP semiconductor material;
• and
• a bottom cell including an emitter and base layer of InGaAs semiconductor material,
• wherein at least one of the base layers has an exponentially doped profile.