Electron tunnelling in Pb/Ag ultrathin layered structures

Abstract

The layered samples are produced by the sequential deposition of lead and silver with thicknesses within the range from 6 to 35 monolayers. The samples about 100 nm thick show X‐ray diffraction spectra characteristic of a superlattice. Measurements of the electron tunnelling spectra of AlAl2O3Pb/Ag layered ultrathin films are performed. Quantum size effects in tunnelling junctions containing 1 to 4 ultrathin layers of lead separated by ultrathin layers of silver are observed. In these oscillations of the tunnelling spectra two sets of different periods are obtained.

Quantum well structures in thin metal films: simple model physics in reality?

“…For these electrons, having energies above the Fermi level, a lifetime of 10 −23 s and a width of 25 meV was estimated, which gave a mean free path of 1000 Å. Later Jalochowski et al [8] extended tunnelling experiments to Pb/Ag sandwiched structures and observed two periods of oscillations. Further experimental work on the QSE exploring the reflectivity and transmission of electrons normally incident on epitaxially grown thin metallic films (of Cu and Ag on a W (110)) was performed by Jonker et al [9][10][11] and Park et al [12,13] (for Cu/Ni(001), Ag/Cu(111), Ag/Si(111) and Cu/Si(111)), Zhu et al [14] and Zdyb et al [15].…”

Derivation of the density of states and distribution functions for two-level systems in glasses

“…While inelastic electron tunneling spectroscopy (IETS) is most famous as a surface vibrational spectroscopy,1-4 there have been a steadily increasing number of papers concerned with the observation of inelastic features in the region above 4000 cm-1 (500 mV). [5][6][7][8][9][10][11] The two best known sources of structure in this region of the tunneling spectrum are electronic transitions of adsorbed species5 and quantum size effect (QSE) structure. [6][7][8][9][10] The theory and experimental information concerning QSE indicate that thin (<100 nm), very smooth, very pure metals must be used.…”

“…[5][6][7][8][9][10][11] The two best known sources of structure in this region of the tunneling spectrum are electronic transitions of adsorbed species5 and quantum size effect (QSE) structure. [6][7][8][9][10] The theory and experimental information concerning QSE indicate that thin (<100 nm), very smooth, very pure metals must be used. In the case of Pb, the deposition must occur below about 150 K with subsequent thermal annealing of the film.…”