Epitaxial Pb films with double positioning have been produced by vacuum evaporation of Pb onto mica substrates maintained at 75 °C during deposition Such films do not exhibit hillock formation when repeatedly cycled between room temperature and 77 °K or annealed at 373 °K This is in contrast to the observation on nonepitaxial Pb films which do exhibit hillock formations when subjected to similar treatments The difference has been interpreted in terms of grain‐boundary orientation and structure

Absence of hillock formation in epitaxial lead films

We report the tunneling characteristics of Pb-Zn-oxide-Pb junctions in which the average Zn thickness is approximately one atomic layer. This thin layer is produced either by indirect evaporation of Zn or by dissociation of ZnS upon evaporation. The tunneling characteristics show an added current shoulder just above the gap-edge voltage similar to that frequently reported for Nb junctions and several other systems, but unexplained until recently. We discuss the McMillan theory of the proximity effect in relation to earlier experiments using thicker normal films. We then use the theory to demonstrate that the observed current shoulder results from the proximity effect, involving a much thinner normal layer than in any previous experiments. A similar effect can explain the observations with Nb and other materials.

Tunneling study of the superconducting proximity effect in the thin-normal limit

Auger spectra have been obtained from Be surfaces prepared under U.H.V. conditions, by thermal cleaning, evaporation and by argon ion bombardment. The resulting Auger spectra from these variously prepared surfaces exhibit different peaks in the dN(E)/dE versus E spectrum which relate to modifications in the band structure. No evidence is found that the difference in the spectra is due to surface impurities. Oxidation effects on the clean Auger spectrum are in agreement with those obtained by others. The temperature variation in the Auger spectrum from clean Be surfaces is discussed in relation to previously reported X-ray investigations.

Auger electron emission from Be surfaces

......................................................................................................................... 113 8.

Muscovite Mica Based Templates for Monolayer Formation and Crystal Growth

Detailed x‐ray diffraction investigations, based on precise measurements of the position, asymmetry, broadening, and shape of x‐ray diffraction profiles 111, 200, 220, 311, 222, and 400 recorded in a counter diffractometer, have been performed on vacuum‐evaporated fcc lead films in the range of thickness ∼300–6500 A. The films are deposited on glass substrates at a residual air pressure ∼5×10−5 Torr for both normal and oblique vapor directions. The complete analyses have revealed clearly the microstructural features in these vapor‐deposited films. Near‐isotropy in the domain size and rms strain values with a relatively less size effect has been observed. The magnitudes of the respective compound fault parameters, close to the error limits, indicate the total absence of intrinsic (α′), extrinsic (α″), and even growth twin (β) stacking faults in the films. The dislocation density (ρ) is typical for thin films and is ∼1011 cm/cm3. The residual internal stresses (σ), compressive in nature, are small, and the ...

An x‐ray diffraction study on the microstructure of vapor‐deposited fcc lead films: normal and oblique incidences

We report the production of (111) epitaxial Pb films on mica and (111) textured Pb films on mica and glass. Film structure is studied by reflection electron diffraction and by etching and optical microscopy. Thin (about 1000 A) epitaxial films are found to be doubly positioned. Reorientation during growth of thicker films leads to single positioning in areas several tenths of a millimeter across.

A. Yelon

Papers

Epitaxy and fiber texture of Pb films on mica and glass.