DETERMINATION OF THE DIFFUSION-COEFFICIENT OF ALUMINUM ALONG THE GRAIN-BOUNDARIES OF GOLD-FILMS BY THE SURFACE ACCUMULATION METHOD

Grain boundary diffusion coefficients of aluminium in polycrystalline gold films were determined in the temperature range 75-110-degrees-C by the surface accumulation method. The time dependence of the average surface concentration of aluminium was followed by X-ray photoelectron spectroscopy (XPS). The obtained grain boundary diffusion parameter could be represented by w(b)D(b) = 2.90 x 10(-12) exp(-1.057 x 10(-19) J/kT) cm-3 s-1. Using the angle-resolved XPS technique the thickness of the surface accumulation layer was estimated to be 0.6 nm. giving for the boundary diffusion coefficient D(b) = 4.8 x 10(-5) exp(-1.057 x 10(-19) J/kT) cm2 s-1. The values of the diffusion coefficients determined from the rate of aluminium accumulation on the surface agreed well with the value estimated from the delay time required for the aluminium to penetrate to the gold surface.