Photovoltaic lead-chalcogenide IR-sensor arrays on Si for thermal imaging applications

Linear arrays of photovoltaic infrared sensors for thermal imaging applications are fabricated in narrow gap semiconductor layers grown heteroepitaxially on Si. Epitaxy is achieved using stacked intermediate BaF2-SrF2-CaF2 buffers to overcome the large lattice as well as thermal expansion mismatch. The arrays consist of 66 elements and cover-off wavelengths ranging from 3 to above 12 fm. Extrapolated resistance-area products of the best PbTe sensors (cut-off wavelength 5.7 fm) on Si are up to 20000 ohm cm2 at 77 K. They appproach those of similar HgCdTe sensors fabricated in bulk or epitaxial material on CdTe substrates.