STR A I N- B ALA N C ED Ino.s2Gao.38As/ I no.47Gao.53As (In P) Q U ANTU M 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 strainbalanced In1 --+ Ga, As/ln 1 -, Ga, As (In P) Quantum Well Cells (QWCs)the absorption can be extended, while retaining a low dark current. We present a strain-balanced In0.6~Gao.3~As/lno.47Gao.53As QWC, which extends the absorption edge beyond that of lattice-matched bulk InGaAs to about 1.8 pm, 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-balancedQWCs. Efficiencies for solar (AM1.5G), black-body spectra of 1500-3200 K and selective emitters are presented. Latticematched InGaAsP and strain-balanced InGaAs (InP) QWCs show superior performance when compared with bulk InGaAs monolithic interconnected modules and bulk GaSb TPV cells.