The growth modes of vapor-deposited Bi on Cu(210)

This work presents growth modes of vapor-deposited Bi on clean and C contam inated Cu(210) surfaces, characterized with low energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscop y (XPS), and work-function shifts (Deltae phi). Up to theta (Bi) = 0.5 ML ( monolayer, ML) fractional Bi coverage (equivalent to 0.686 x 10(15) at. cm( -2)) a p(1 x 1) structure is observed, associated with a gradual LEED patte rn symmetry change from one mirror plane for clean Cu(2 1 0) to two, for OH , = 0.5 ML. The higher symmetry phase is stable up to 723 K, and no appreci able binding-energy shifts are detected by XPS in the Bi (4f(7,2)) and Cu ( 2p(3,2)) core lines. Additional Bi results in Stranski-Krastanov growth of a compact Cu(2 1 0)-(6 x 1)-Bi structure with eight Bi atoms per unit cell, stable up to 628 K. Impurity levels of both either pre or coadsorbed C low er the stability temperature of the (6 x 1)-Bi phase. However, C does not h ave any appreciable influence on the p(1 x 1)-Bi phase. The presence of as little as theta (C) = 0.1 ML of preadsorbed C produces Frank-Van der Merwe (layer by layer) growth of the p(1 x 1) c2mm structure, up till completion of the third layer, and as much as 30% variation in Deltae phi values with respect to C-free samples. Carbon appears to have no effect on the growth, at 723 K, of Cu(2 1 0) p(1 x 1)-Bi facets from the Cu(1 0 0)-c(2 x 2)-Bi ph ase when sufficient defects (vacancies) are present in the selvedge. (C) 20 01 Elsevier Science B.V. All rights reserved.