High-quantum-efficiency 0.5 eV GaInAsSb/GaSb thermophotovoltaic devices

We report high-performance lattice-matched GaInAsSb/GaSb thermophotovoltaic (TPV) devices with a 0.5 eV band gap. The TPV structures were grown on GaS b substrates by organometallic vapor phase epitaxy at a lower temperature ( 525 degrees C compared to 550 degrees C) to improve the quality of the meta stable GaInAsSb alloy. The 0.5 eV TPV devices exhibit external quantum effi ciency as high as 60%, which corresponds to an internal quantum efficiency of 90%, assuming 35% reflection losses. This efficiency is comparable to th e value measured for 0.53 eV devices. The ratio of the open circuit voltage to band-gap energy ratio decreases from 0.57 for 0.53 eV devices to 0.48 f or 0.5 eV devices. (C) 1999 American Institute of Physics. [S0003-6951(99)0 0935-3].