Galvanomagnetic properties of single-crystal bismuth-antimony thin films

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Abstract
Describes growth of the first thin ( approximately 1 mu m) epitaxial films of pure bismuth-antimony alloys using molecular beam epitaxy techniques. These structures were grown at elevated temperatures on single-crystal barium fluoride substrates of (111) orientation. Electron microscope observations show the films to be featureless and defect-free on the scale of 0.1 mu m. The films grow with their trigonal axis parallel to the (111) axis of the substrate, and Laue-backscattering pictures show that they are epitaxial. Mobilities of alloys with x=0 are of the order of 2 m2 V-1 s-1 at room temperature and increase to over 10 at 20 K and 100 at liquid helium temperatures. These values are far superior to those of other bismuth films grown to data, and approach mobilities observed in single-crystal bismuth. The dependence of energy gap and c axis lattice constant on x is different from that in bulk alloys, which may be due to the effects of strain arising from the 3.6% lattice mismatch between sample and substrate.