Résumé
Very-low bandgap thermophotovoltaic (TPV) cells are rather well-suited for maximizing the power output of TPV systems. However, such low bandgap materials (< 0.5 eV) usually suffer from high dark current densities, and require cryogenic cooling for acceptable performance. In this study, we present the fabrication and characterization of a TPV cell made of an InAs/InAsSb superlattice absorber (0.25 eV) and an AlAsSb barrier layer, meant to reduce the dark current. Details on the growth of the samples, clean room processing and electrical characterization are provided. Measurements indicate that the barrier layer is able to supress surface current and overall reduce the dark current by a few decades compared to a PIN structure. Under the illumination of a 800 • C thermal emitter, the design proposed was able to increase the power output of the cell by more than tenfold for temperatures above 150 K. A photovoltaic effect is even observed at room temperature.