Atomic structure of a regular Si(223) triple step staircase

International audienceAn atomically accurate regular triple step array with a period of 4.8 nm has been fabricated on the vicinal Si(5 5 7) surface. Its atomic structure was studied on different length scales by scanning tunneling microscopy, low energy electron diffraction and photoelectron spectroscopy. These complementary methods allowed to identify the average orientation of the regular triple step staircase as Si(2 2 3) and to give a deeper insight into the atomic arrangement of this structure. (c) 2009 Elsevier B.V. All rights reserved

Simulation of Lead Nanoislands Growth using Density Functional Theory

International audienceMany metals adopt a face-centered cubic structure in their bulk form, but they often exhibit important structural and morphological deviations when confined to nanoscale or interacting with the environment. In this paper, the growth of lead nanoislands on silicon(111) has been investigated in ultrahigh vacuum for different evaporation conditions: temperature, flux, annealing time, and source or surface condition. Unexpected Pb icosahedral nanoparticles of a very large, up to 100 nm, size have been revealed to grow on Si(111) substrate. The coexistence between these 5-fold twinned Pb pyramids and expected face-centered cubic (fcc) Pb single crystals has been investigated in situ by Scanning Tunneling Microscopy (STM) and ex situ by Scanning Electron Microscopy (SEM). We found that the growth of the Pb icosahedral particles only occurs when very high Pb diffusion conditions are met, with a high quality of the silicon surface and a purified lead source. The icosahedral pyramids have been observed to be more stable upon ripening at room temperature than fcc single crystals

Regular stepped structures on clean Si(hhm)7x7 surfaces

International audienceRegular single and triple step arrays with different periodicities have been fabricated in ultrahigh vacuum on clean Si(557) surfaces at various thermal treatment procedures. The atomic structure of the triple step staircases has been studied with high resolution scanning tunneling microscopy (STM). The results of atomically resolved STM experiments demonstrate a number of possible triple step configurations on Si(hhm) surfaces. The triple step models consistent with atomically resolved STM data obtained on regular Si(223) and Si(556) triple step staircases are presented. Possible driving forces for self-assembling regular step arrays on large scale areas are discussed