Low-bandgap PV and thermophotovoltaic cells

The performance of GaSb cells was improved by optimization of diffused emitter, which allowed increasing efficiencies up to 11% under AMO spectrum and 19% under the part of AMO spectrum with /spl lambda/ > 900 nm at photocurrent of 2-7 A/cm/sup 2/. By means of LPE growth and Zn diffusion, TPV cells based on (p-n)-InAsSbP/n-InAs and (p-n)-InAs structures sensitive in the range of (2.5-3.4) /spl mu/m were fabricated. Zinc-diffused (p-n)-Ge based PV cells were fabricated with short circuit current density of 31.6 mA/cm/sup 2/ at 8% shadowing and of 33.2 mA/cm/sup 2/ obtained from the spectral curve of the internal quantum yield at active area under sunlight with /spl lambda/ > 900 nm AMO spectrum. Ge cells with GaAs windows were developed by the combination of LPE or MOCVD growth of GaAs and Zn-diffusion. Efficiency higher than 13% was obtained in p-GaAs/(p-n)- Ge cells with under cut off /spl lambda/ > 900 nm AMO spectrum at photocurrent densities of 3-25 A/cm/sup 2/.