Competing allotropes of Bi deposited on the Al13Co4(100) alloy surface

Stefania Bobaru (1) , Emilie Gaudry (1) , Marie-Cécile de Weerd (1) , Julian Ledieu (1) , Vincent Fournée (1)

1 IJL - Institut Jean Lamour

The growth and stability of Bi thin films on the Al13Co4(100) surface has been investigated from the submonolayer to high-coverage regime by scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) for temperatures ranging from 57 to 633 K. Initially, Bi adsorption leads to the formation of a pseudomorphic monolayer, followed by the growth of islands of different heights with increasing coverage. The in-plane structure, island height, and island morphology indicate that these islands adopt either a pseudocubic (110) or hexagonal (111) orientation normal to the surface. The (110)-oriented islands correspond to bilayer stacking (either two or four monolayers in height) while the (111)-oriented islands correspond to either three- or four-layer stacking. The in-plane orientation of (110) islands with respect to the substrate is random, while (111) islands adopt one of four possible orientations. In addition, the (111) islands show a moiré structure. The fact that Bi islands grow with either (110) or (111) orientation simultaneously on the same substrate relates to a subtle energy balance between both orientations according to ab initio calculations, allowing both structures to coexist. The island density dependence versus both deposition temperature and flux, their most frequent structure type, reshaping effects, and chemical reactivity of the different allotropes are also discussed in this paper.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Stefania Bobaru, Emilie Gaudry, Marie-Cécile de Weerd, Julian Ledieu, Vincent Fournée. Competing allotropes of Bi deposited on the Al13Co4(100) alloy surface. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2012, 86 (21), pp.214201. ⟨10.1103/PhysRevB.86.214201⟩. ⟨hal-00974263⟩