Growth of high quality epitaxial PbSe onto Si using a (Ca,Ba)F2 buffer layer

Epitaxial layers of PbSe have been grown onto Si(111) by vacuum deposition techniques using a (Ca,Ba)F2 buffer film. For lattice match, the buffer layer is graded with CaF2 at the Si interface and BaF2 at the PbSe interface. Like bulk BaF2, this buffer layer forms a suitable support for the growth of high quality PbSe. The layers grown exhibit smooth surfaces and mobilities as high as those of bulk PbSe, i.e., ∼3×104 cm2 V−1 s−1 at 77 K and >1.2×105 cm2 V−1 s−1 below 20 K. These results are very promising for the fabrication of heteroepitaxial monolithic integrated circuits, with, for example, photovoltaic (Pb,Sn) (S,Se,Te) narrow gap semiconductor infrared detectors on silicon.