The epitaxial growth of lead and thallium on (111) silver and copper

Abstract

A combination of LEED, RHEED and AES has been used to observe lead and thallium growing in a layer-by-layer manner on (111) silver, and in the Stranski-Krastanov mode on (111) copper. Ordered sub-monolayer structures were observed for growth on the silver substrate but not for the copper substrate. However, for growth on the copper substrate a substantial contraction in the lead and thallium nearest-neighbour spacing ( approximately 3%) was observed at an approximately one monolayer coverage. It is suggested that the resulting strain in the overlayer may be responsible for the Stranski-Krastanov growth mode. Non-parallel epitaxial layers were formed by lead on silver, and by thallium on both copper and silver. The occurrence of such deposits may be linked with directional bonding forces at the interface, and/or stabilised via the existence of low-angle tilt boundaries in the overgrowth.

Two-dimensional Pb–Sn alloy monolayer films on Ag(111)

“…There are two equivalent domains for the Pb overlayer films, which is rotated ±4.5 • with respect to the Ag (1 1 1). These results are consistent with previous reports [8,13]. When the Pb coverage increases higher than 0.65 ML, a second layer Pb film is formed, as shown in Fig.…”

Atomic structure at electrode interfaces

“…The open circles represent atoms of the Ag(lll) surface, while the shaded circles represent the Tl adatoms. This structure is the same as for vapor deposited Tl/Ag(lll) (9), which shows that the monolayer structure is not influenced by the presence of solvent molecules near the interface. This contrasts to Special Report some other systems, for example Cu/Au( 111), where the electrolyte is an important factor in determining the adlayer structure (10).…”

Orbital selective overlayer-substrate hybridization in a Pb monolayer on Ag(111)

“…The annealing temperature for the clean Ag͑111͒ crystal was 800 K, while the post-annealing temperature with the Pb monolayer was 500 K. The structural quality has been verified by low energy electron diffraction ͑LEED͒ which showed a typical moiré diffraction pattern. 17 The base pressure was Ͻ1 ϫ 10 −10 mbar. ARPES measurements were done at 77 and at 300 K using HeI radiation ͑21.2 eV͒.…”