Patent ID: 8049100

Claim:
A structure within a solid state device comprising at least two photovoltaic cells in tandem; the structure comprising; a first solar cell of first composition comprising first and second surfaces; a second region of second composition comprising first and second surfaces; and a second solar cell of third composition comprising first and second surfaces separated from the first region by the second region; the first solar cell and second solar cell being arranged in tandem; wherein the second region consists substantially of first and second rare-earth oxide compounds such that the lattice spacing of the first rare-earth oxide compound is different from the lattice spacing of the second rare-earth oxide compound and wherein the first and second solar cells consist substantially of elements only from Group IV and the third composition is different from the first composition and the first surface of the second region is in contact with substantially all of the second surface of the first solar region and the second surface of the second region is in contact with substantially all of the first surface of the second solar cell and wherein the composition of the second region consists substantially of [RE1] v [RE2] w [RE3] x [J1] y [J2] z wherein [RE] is chosen from a rare earth; [J1] is oxygen and [J2] is chosen from a group consisting of Oxygen (O), Nitrogen (N), and Phosphorus (P), and 0≦v, z≦5, and 0≦w, x, y≦5.