Study of Ultrathin In-Ag Layers on Tungsten by Means of Surface Spectroscopy Techniques
A. Bukaluk, M. Trzcinski and K. Okulewicz
Institute of Mathematics and Physics, University of Technology and Life Sciences, Kaliskiego 7, PL-85-796 Bydgoszcz, Poland
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Received: 16 05 2008
Auger electron spectroscopy, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, scanning tunnelling microscopy, low energy electron diffraction, and thermodesorption methods were used to investigate the process of growth of ultrathin In films and formation of In-Ag surface alloys on tungsten substrate. Several indium layers, having coverage ranging from 0.2 to 0.8 ML were deposited on tungsten substrate in room temperature. It was found that at the lowest coverages (Θ= 0.1-0.3 ML) indium atoms form (3×1) structure, characterized by very sharp low energy electron diffraction patterns. With increasing Θ they tend to form densely packed islands interpreted as slightly distorted In(111) monolayers. Surface diffusion of In onto the tungsten surface was studied by using ESCA imaging property of SCIENTA ESCA200 instrument. Measuring the photoelectron intensity as a function of two spatial coordinates and the energy, we observed movement of In atoms on the tungsten surface. On the basis of the change of surface coverage with distance surface the diffusion coefficient was evaluated at the temperature range of 400-700 K. Intermixing of ultrathin films of indium and silver, after their surface diffusion from the sample edges to the centre of the tungsten surface, were observed by using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and the Auger electron spectroscopy methods. Intermixing was controlled by means of photoemission spectra from the valence states and the In 4d level, as well as by X-ray photoelectron spectroscopy studies of indium and silver core levels excited by Al Kα source.
DOI: 10.12693/APhysPolA.114.S-17
PACS numbers: 61.05.jh, 61.46.Hk, 61.66.Dk, 68.37.Ef