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The conductivity of thin films of thallium on a pyrex glass surface

1939; IOP Publishing; Volume: 51; Issue: 2 Linguagem: Inglês

10.1088/0959-5309/51/2/312

2051-2171

J. R. Bristow,

Metal and Thin Film Mechanics

Thin films of thallium have been prepared by condensation of the metal on a cooled pyrex surface at a pressure of 10-7 mm. of mercury or less. At a thickness of more than 40 A. the films show a resistivity only about three times greater than that of the bulk metal. The results tend to substantiate the views of Appleyard and Lovell that evaporated films do not differ radically in structure from the bulk metal, at least after the first few atomic layers. The thallium films described here differ in an important respect from both the alkali films and from mercury. Unlike the alkali-metal films they show no conductivity until the film is about five atomic layers in thickness; and unlike mercury films, which show a similar delayed conductivity, they have a finite range of thickness in which the resistivity is very high. It seems possible that the material is only semiconducting in this range, possibly owing to distortion of the normal metallic lattice by the atoms of the substrate.