Heteroepitaxial Pb1−<i>x</i>Sn<i>x</i>Se on Si infrared sensor array with 12 μm cutoff wavelength

Abstract

An array of photovoltaic infrared sensors with 12 μm cutoff wavelength has been fabricated for the first time in a narrow-gap semiconductor layer grown heteroepitaxially on Si. Heteroepitaxy is achieved using intermediate stacked epitaxial CaF2-SrF2-BaF2 buffer layers to overcome the large lattice as well as thermal expansion mismatch between narrow-gap Pb1−xSnxSe and Si. The IR sensors exhibit resistance-area products up to 0.3 Ω cm2 at 77 K. This corresponds to sensitivities which are above the 300 K background noise limit and only 2–5 times lower than those of state of the art Hg1−xCdxTe sensors on CdZnTe substrates with the same cutoff wavelengths.