Patent ID: 8101856
Filing Date: 2012-01-24
Classification: B82Y,H01L,Y02E

Abstract:
1. A tandem photovoltaic cell device comprising: a bottom silicon cell comprising a lightly p-doped silicon layer formed on top of a P+ doped silicon region which has a back surface including a passivating dielectric layer composed of silicon dioxide or amorphous silicon; a tunnel junction comprising an N+ doped silicon layer formed on top of said lightly p-doped silicon region and a P+ silicon layer formed upon said N+ doped silicon layer; an upper (Gallium Phosphide) GaP photovoltaic cell comprising a a lightly P− doped GaP layer formed on top of said P+ doped silicon layer of said tunnel junction and an N+ doped top layer formed thereabove; at least one pseudomorphic, epitaxial, quantum well layer composed of a material other than GaP having a bandgap less than that of GaP formed between said lightly P-doped p-type GaP region and said N+ doped top layer; with said at least one quantum well layer having a lattice constant and thickness compatible with said lightly doped p-type GaP layer; said at least one quantum well layer comprising a depletion region formed between said N+ doped GaP layer and said lightly doped p-type GaP layer of said upper GaP photovoltaic cell; said upper GaP photovoltaic cell incorporating at least one layer of a semiconductor material for absorbing radiant energy within said depletion region of said N+ GaP junction; electrical means of contacting said upper GaP photovoltaic cell and said bottom silicon photovoltaic cell; and said at least one layer of material within said depletion region consists of at least one material selected from the group consisting of GaAs, GaAsP, GaInAs, GaInP, and GaInAsP.