A new method was described which involved the use of variable temperature scanning tunnelling microscopy to determine the onset temperature for the diffusion of self-interstitial atoms. The interstitials were produced by the low-fluence 4.5keV Ne+ bombardment of Pt(111) at 20K. At 22K, the interstitials became mobile and migrated to the surface, where they could be detected as new adatoms, using scanning tunnelling microscopy. It was thus possible to investigate the number and diffusivity of interstitials that were produced close to the surface. Under the present bombardment conditions, a single impact produced at least one freely migrating interstitial. By using a 1-dimensional model for diffusion, it was deduced that the results could be described by an activation energy of 0.05eV and a frequency-factor of 6 x 1011/s. These parameters were in reasonable agreement with those deduced from resistance/annealing curves.

M.Morgenstern, T.Michely, G.Comsa: Physical Review Letters, 1997, 79[7], 1305-8