Influence of the substrate temperature and deposition flux in the growth of a Bi thin film on the ten-fold decagonal Al-Ni-Co surface

Abstract

We compare the growth of a Bi thin film on the ten-fold surface of the decagonal Al-Ni-Co quasicrystal at different substrate temperatures and fluxes using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The growth at 29 K leads to the formation of a quasicrystalline monolayer, consistent with the results obtained at 300 K. Further deposition at low temperature produces pseudocubic islands with {100} surface orientation. The islands have two or four atomic layer heights. Both STM and LEED measurements reveal that there is a transition from the pseudocubic {100} film to the hexagonal {0001} surface orientation at coverage (θ) 4 < θ < 6 ML. The hexagonal domains are oriented along the high symmetry directions of the substrate. Growth at room temperature with different fluxes results in different island-height distributions. High flux predominantly produces islands of uniform four-layer high islands, whereas low flux yields islands of varying heights, yielding a rough film morphology. The two-layer high islands are found to be more stable at low temperature than at room temperature.

Keywords:

• Al-Ni-Co
• quasicrystal
• Bi
• thin film
• scanning tunneling microscopy
• low energy electron diffraction

Acknowledgements

This work was supported by the Engineering and Physical Sciences Research Council (Grant No. EP/D071828/1 and EP/DO5253X/1). The European Network of Excellence on ‘Complex Metallic Alloys’, Contract No. NMP3-CT-2005-500145, and the Agence Nationale de la Recherche, Reference No. ANR-07-Blan-0270, are thanked for their financial support. We thank R. McGrath and J. Smerdon for helpful discussions.