Abstract
When tantalum field emission microscope tips are heated in the presence of applied electric fields, the build-up of the 〈111〉 areas dominates. A linear relationship is indicated between the activation energy for surface self-diffusion, Q F, determined from this process and log p ( p average residual gas pressure during the measurement). The negative slope is interpreted in terms of the presence of a permanent dipole migration mechanism. At p=5×10 −10Torr and F apex=22 MV/cm, Q F≅1.4 eV/particle. From the build-up decay the corresponding activation energy for surface self-diffusion without applied field Qs=2.03±0.05 eV/particle could be determined. The higher values obtained by other authors are explained by the influence of contaminants.
Published Version
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