Nonequilibrium behavior of the Pb wetting layer on Si(111)7x7

TitleNonequilibrium behavior of the Pb wetting layer on Si(111)7x7
Publication TypeJournal Article
Year of Publication2011
AuthorsGramlich MW, Hayden ST, Chen YY, Kim C, Conrad EH, Tringides MC, Miceli PF
Journal TitlePhysical Review B
Date Published08
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000293618900018
KeywordsISLANDS, low-temperature growth, metal-films, nanocrystals, PB/SI(111)-(7X7), phase-transitions, surfaces, UNIFORM

The growth and stability of the Pb8x8 wetting layer on Si(111)7x7, which provides a foundation for growing quantum-size-effect nanocrystals, was investigated by in situ x-ray scattering. Our experimental results reveal that the wetting-layer structure evolves temporally over a remarkably broad range of temperatures and that there are two distinct temperature regimes of nonequilibrium behavior. When grown at lower temperature (below 170 degrees C), it was discovered that the wetting-layer structure changes with time, indicating that its disordered structure is not static; annealing in this regime improves the order of the wetting layer. Growth at higher temperature (170 degrees C < T < 250 degrees C), however, leads to a time-dependent degradation of the 8x8 structure due to the deterioration of the underlying Si(111) 7 x 7. Thermal measurements determined an activation energy of 0.4 eV in the low-temperature regime, whereas in the high-temperature regime, a two-step process is observed, which has activation energies of approximately 1.3 and 1.9 eV. The results provide important considerations for understanding the anomalous kinetic behavior of quantum-size-effect Pb nanocrystals on Si(111)7x7, which is facilitated by the wetting layer.

Alternate JournalPhys. Rev. B