Strain-balanced In/sub 0.62/Ga/sub 0.38/As/In/sub 0.47/Ga/sub 0.53/As(InP) quantum well cell for thermophotovoltaics

For thermophotovoltaic (TPV) applications, there is considerable interest at present in extending the absorption to longer wavelengths for higher overall system efficiencies with lower temperature sources. With strain-balanced In/sub 1-x/Ga/sub x/As/In/sub 1-y/Ga/sub y/As (InP) quantum well cells (QWCs) the absorption can be extended, while retaining a low dark current. We present a strain-balanced In/sub 0.62/Ga/sub 0.38/As/In/sub 0.47/Ga/sub 0.53/As QWC, which extends the absorption edge beyond that of lattice-matched bulk InGaAs to about 1.8 /spl mu/m, which is similar to that of GaSb, while the dark current remains at a lower level. We can model the spectral response of InP-based-including strain-balanced-QWCs. Efficiencies for solar (AM1.5G), black-body spectra of 1500-3200 K and selective emitters are presented. Lattice-matched InGaAsP and strain-balanced InGaAs (InP) QWCs show superior performance when compared with bulk InGaAs monolithic interconnected modules and bulk GaSb TPV cells.