Shubnikov-de Haas effect in thin epitaxial films of gray tin

The transverse magnetoresistance and Hall effect have been studied for n-type gray tin epilayers grown on (001)CdTe substrates by the molecular beam epitaxy technique. Shubnikov-de Haas oscillations were observed in samples having Hall mobilities ≥10⁴ cm² /V s at low temperatures. Measurements were carried out using both the dc method and field modulation techniques in the temperature range from 1.2 to 10 K and in magnetic fields up to 10 T. Beat patterns were observed in the Shubnikov-de Haas spectra which we ascribe either to inhomogeneous doping, arising from the diffusion of Cd and Te from the substrate, or to quantization of the motion in the direction parallel to the film normal. The Shubnikov-de Haas carrier concentration of a 1210 Å film was determined to be n_SdH =2.3×10 ¹⁷ cm^-3, in good agreement with the Hall density.