Multijunction solar cell and solar cell assemblies for space applications

A method of fabricating a multijunction, space-qualified solar cell, comprising:

• providing a growth substrate;
• forming an upper first solar subcell on the growth substrate composed of indium gallium phosphide and having a first band gap in the range of 2.0 to 2.2 eV;
• growing a second solar subcell adjacent to said first solar subcell and including an emitter layer composed of indium gallium phosphide or aluminum indium arsenide, and a base layer composed of aluminum indium gallium arsenide and having a second band gap in the range of approximately 1.55 to 1.8 eV and being lattice matched with the upper first solar subcell, wherein the emitter and base layers of the second solar subcell form a photoelectric junction;
• growing a third solar subcell adjacent to said second solar subcell and composed of indium gallium arsenide and having a third band gap less than that of the second solar subcell and being lattice matched with the second solar subcell;
• and
• growing a fourth solar subcell adjacent to said third solar subcell and composed of germanium and having a fourth band gap of approximately 0.67 eV.