Tunneling-spectroscopy study of the electron spectrum in bismuth films
Annotatsiya
The dV/dI characteristics have been obtained for the Al-I-Bi, Sn-I-Bi, and Bi-I-Sn systems. The tunnel junctions are produced on a bismuth film of varying thickness, so that it is possible to compare the characteristics of tunneling systems of approximately the same quality but with different film thicknesses. The nonlinearities found on the tunneling characteristics are considered a manifestation of features in the distribution of the electron state density in the semimetal. The oscillations on the characteristics are due to the quantum size effect. However, the oscillation pattern turns out to be more complicated than would be expected on the basis of the simple model of the quantum size effect associated with electrons in a rectangular potential well with infinitely high walls. The dV/dI characteristics reveal a displacement of the features corresponding to the characteristic points in the semimetal spectrum as the film thickness changes. These shifts correspond to an increase in the chemical potential with decreasing thickness of the bismuth film An inhomogeneous potential distribution in the semimetal film is offered as a model to explain these results.