Minority-carrier transport in InGaAsSb thermophotovoltaic diodes

摘要

Uncoated InGaAsSb/GaSb thermophotovoltaic (TPV) diodes with 0.56 eV (2.2 (micro)m) bandgaps exhibit external quantum efficiencies of 59% at 2 (micro)m. The devices have electron diffusion lengths as long as 29 (micro)m in 8-(micro) m-wide p-InGaAsSb layers and hole diffusion lengths of 3 (micro)m in 6-(micro)m- wide n-InGaAsSb layers. The electron and hole diffusion lengths appear to increase with increasing p- and n-layer widths. At 632.8 nm the internal quantum efficiencies of diodes with 1- to 8-(micro)m-wide p-layers are above 89% and are independent of the p-layer width, indicating long electron diffusion lengths. InGaAsSb has, therefore, excellent minority carrier transport properties that are well suited to efficient TPV diode operation. The structures were grown by molecular-beam epitaxy.