Room-temperature InAs0.89Sb0.11 photodetectors for CO detection at 4.6 mm

An InAs0.89Sb0.11 photovoltaic detector that operates at room temperature in the 2.5–5 mm mid-infrared wavelength region is reported. The photodiode has an extended spectral response compared with other currently available III–V room-temperature detectors. In order to accommodate the large lattice mismatch between the InAs0.89Sb0.11 active region and the InAs substrate, a buffer layer with an intermediate composition was introduced into the structure. In this way, we obtained room-temperature photodiodes with a cutoff wavelength near 5 mm, a peak responsivity of 0.8 A/W, and a detectivity of 1.26310 cm Hz/W. These devices could be effectively used as the basis of an optical sensor for the environmental monitoring of carbon monoxide at 4.6 mm, or as a replacement for PbSe photoconductors. © 2000 American Institute of Physics. @S0003-6951~00!02332-9#