Mid-IR photovoltaic devices based on interband cascade structures

Progress in the design and implementation of interband cascade (IC) structures for thermophotovoltaic (TPV) applications is reported. These devices were designed with enhanced electron barriers and p-type InAs/GaSb superlattice absorbers. These features have been shown to be successful in suppressing dark current in photodetectors. Our seven stage devices had cutoff wavelengths of 4.0 μm at 80 K and 5.0 μm at 300 K. Good photoresponse and dark current suppression was observed at low temperatures. Under illumination of a 1200 K blackbody, a short-circuit current of 5.46 A/cm² and open-circuit voltage of 1.61 V were observed for a device temperature of 80 K. Above 80 K, we were able to observe high values of the open circuit voltage up to 180 K.