GaAsP/lnGaAsN strained layer superlattices for solar cell applications

GaAsP/InGaAsN strained layer superlattices (SLSs), lattice matched to GaAs, are proposed to extend the long wavelength absorption of the bottom cell in a cascade solar cell structure. In the proposed SLS structure, the In content can be higher than in conventional InGaAsN bulk films and the N content maintained near 1% while still maintaining the lattice matching condition to the GaAs substrate. With this approach, we can avoid the fairly high N concentration in the InGaAsN alloy that can deteriorate electrical properties. Data are presented for GaAsP/lnGaAs SLSs that validate this approach and which lay a framework for the successful development of the GaAsP/InGaAsN SLS structure.