Heteroepitaxial Pb1-xSnxSe on Si infrared sensor array with 12 mym cutoff wavelength.

An array of photovoltaic infrared sensors with 12 mym 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 PbSnSe and Si. The IR sensors exhibit resistance-area products up to 0.3 (ohm cm square) 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 HgCdTe sensors on CdZnTe substrates with the same cutoff wavelengths