Heteroepitaxial Pb1−xSnxSe on Si infrared sensor array with 12 μm cutoff wavelength

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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.