Observation of the Shubnikov–de Haas effect in thin bismuth films
Annotatsiya
Through recording of the derivative ∂R/∂H as a function of the magnetic field intensity H over the 0–50 kOe range at 4.2 °K in epitaxial 1300–4000-Å-thick bismuth films, it was possible to detect Shubnikov-de Haas oscillations corresponding to magnetic quantization in the hole band. Large-amplitude Shubnikov-de Haas oscillations were observed in the field dependence of the derivative ∂VH/∂H and of the Hall component VH+,VH− itself directly, which has been found to be another manifestation of magnetic quantization in the hole band. The period of all observed Δ(H−1) oscillations was found to vary appreciably with varying film thickness L, namely to decrease from ∼3 · 10−5 Oe−1 at the maximum thickness to 1.8 · 10−5 Oe −1 at 1500 Å, while remaining larger than the corresponding known period (1.6 · 10−5 Oe−1) for holes in a pure bulk bismuth crystal with an analogous orientation of the crystallographic axes. The decrease of the Δ(H−1) period with decreasing film thickness L corresponds to the result, obtained earlier with with the aid of measurements of kinetic characteristics of a bismuth film, that indicates an increase in the concentrations of both types of charge carriers with a decrease in the bismuth film thickness, and is explainable on the basis of the model of a nonuniform film potential.