Inverted metamorphic solar cell with via for backside contacts

A method of manufacturing a solar cell having a front side and back side comprising:

• providing a first substrate;
• depositing on said substrate a sequence of layers of semiconductor material that forms at least one cell of a multifunction solar cell;
• providing a second substrate over said second region;
• removing said first substrate;
• forming a first electrode on the back side of the solar cell;
• and
• forming an electrical connection between the top cell of the multijunction solar cell and a second electrode on the back side of the solar cell.

A multijunction solar cell comprising:

• a first solar subcell having a first band gap;
• a second solar subcell disposed over said first subcell and having a second band gap small than said first band gap;
• a grading interlayer disposed over said second subcell and having a third band gap greater than said second band gap;
• a third solar subcell disposed over said interlayer that is lattice mismatched with respect to said second subcell and having a fourth band gap smaller than said third band gap;
• and
• anode and cathode contacts to said solar cell disposed on the surface of said solar cell adjacent said third solar subcell.