Investigation of the spectrum of surface states in bismuth by scanning tunneling spectroscopy

Abstract
Scanning tunneling spectroscopy of trigonal (0001) and “quasitrigonal” surfaces of a twin interlayer on a cleaved face of bismuth is performed. It is found that both surfaces are characterized by surface electron states with spectra exhibiting clearly defined singularities, namely, relatively narrow maxima and minima of the density of states in the energy range of ∓1 eV. An analysis of the behavior of the current-voltage characteristics at low (of the order of tens of millivolts) voltages has revealed the existence on the bismuth surface of a two-dimensional layer, in which the density of states of electrons, unlike its anomalously small value in the bulk of bismuth, is of the order of magnitude typical of metals.