One-Dimensional Diffusion of Pb Atoms on the Si(553)-Au Surface

Abstract

One-dimensional diffusion along long atomic chains of the Si(553)-Au surface is studied with scanning tunneling microscopy. Ab initio calculations reveal aligned preferential adsorption sites between Si step edge atomic chain and double Au atomic chain on each terrace. At 220 K the Pb atoms hop between shallow potential basins forming a potential groove and move parallel to the atomic chains. By combining the results of measurements with the model calculations of the Pb atoms static energy on the Si(553)-Au surface the attempt frequency ν₀ is determined.

Surface diffusion of Pb atoms on the Si(553)-Au surface in narrow quasi-one-dimensional channels

“…2 of Ref. [26]). Thus it is not clear if the diffusion channels are really located near the step edges of the surface.…”

“…In simulations the electron work functions Figure 1 shows the (a) filled and (b) empty states STM topography images of the same area of the Si(553)-Au surface, recorded at temperature T = 220 K. As it was discussed in Ref. [26], the filled states STM topography [ Fig. 1(a)] reproduces well the morphology of the bare Si(553)-Au surface, i.e., before the deposition of Pb.…”

“…No jumps across the steps have been observed at room temperature. According to density functional theory (DFT) calculations [26,27], the diffusion channels are composed of shallow energy barrier series, ranging from 0.18 * mariusz.krawiec@umcs.pl to 0.42 eV. In the perpendicular direction the movement of Pb atoms is limited by as high as 1 eV energy barriers, which explains the absence of interchannel jumps in the experiment.…”

“…However, the movement of atoms can become strongly anisotropic or even quasi-one-dimensional in the presence of a specific surface reconstruction or on stepped (vicinal) templates [23][24][25][26][27][28].…”

“…Recently, using scanning tunneling microscopy (STM), we have discovered the one-dimensional diffusion of Pb atoms on the Si(553)-Au surface at temperatures above 110 K [26]. Due to a regular morphology of the Si(553)-Au surface, featuring equally spaced steps and a low number of defects [29][30][31][32], it was possible to observe an unusual long-range one-dimensional mobility of individual Pb atoms.…”