InGaAsSb thermophotovoltaic diode: Physics evaluation

The hotside operating temperatures for many projected thermophotovoltaic (T PV) conversion system applications are approximately 1000 degrees C, which sets an upper limit on the TPV diode band gap of 0.6 eV from efficiency and power density considerations. This band gap requirement has necessitated t he development of new diode material systems never previously considered fo r energy generation. To date, InGaAsSb quaternary diodes grown lattice matc hed on GaSb substrates have achieved the highest performance. In this artic le we relate observed diode performance to electro-optical properties such as minority carrier lifetime, diffusion length, and mobility and provide in itial links to microstructural properties. This analysis has bounded potent ial diode performance improvements. For the 0.53 eV InGaAsSb diodes used in this analysis (active layer doping is 2 x 10(17) cm(-3)) the dark current density measured is 2 x 10(-5) A/cm(2) versus a potential Auger and/or a ra diative limit of 2 x 10(-6) A/cm(2) (no photon recycling!, and an absolute thermodynamic limit of 1.4 x 10(-7) A/cm(2). These dark current limits are equivalent to open circuit voltage gains of 60 (20%) and 140 mV (45%), resp ectively. (C) 1999 American Institute of Physics. [S0021-8979(99)05704-7].