MULTI-JUNCTION III-V SOLAR CELL

摘要

A multi junction solar cell structure includes a top photovoltaic cell including III-V semiconductor materials and a silicon-based bottom photovoltaic cell. A thin, germanium-rich silicon germanium buffer layer is provided between the top and bottom cells. Fabrication techniques for producing multi junction III-V solar cell structures, lattice-matched or pseudomorphic to germanium, on silicon substrates is further provided wherein silicon serves as the bottom cell. The open circuit voltage of the silicon cell may be enhanced by localized back surface field structures, localized back contacts, or amorphous silicon-based heterojunction back contacts.

主权项

1. A multi junction solar cell structure comprising:
a top photovoltaic cell having a bandgap between 1.8-2.1 eV, the top photovoltaic cell including a first base layer and a first emitter layer adjoining the first base layer, the first base and emitter layers each being comprised of a III-V semiconductor material; a bottom photovoltaic cell including a second base layer and a second emitter layer adjoining the second base layer, the second base and emitter layers each being comprised of silicon; a buffer layer between the top and bottom photovoltaic cells, the buffer layer comprising silicon and germanium and having a germanium-rich portion, the top photovoltaic cell being lattice matched or pseudomorphic to the germanium-rich portion of the buffer layer, and a tunnel junction between the top photovoltaic cell and the buffer layer.