Homoepitaxial growth of Bi(111)

Abstract

Homoepitaxial growth of Bi͑111͒ at temperatures between 80-300 K has been studied using spot profile analyzing low-energy electron diffraction ͑SPA-LEED͒ and scanning tunneling microscopy ͑STM͒. From the intensity oscillations of the ͑00͒-spot with Bi coverage and the STM topography of two-dimensional ͑2D͒ islands at low coverage, a pure 2D nucleation followed by a quasi bilayer-by-bilayer growth mode has been confirmed. The oscillation amplitude decays slowly with coverage, indicating a slow kinetic roughening due to a weak Ehrlich-Schwoebel step edge barrier. From the Arrhenius behavior of the average island separation an intraterrace diffusion barrier of E d = 0.135 eV is estimated. Regularly ordered quasidendritic shape islands reflect an asymmetry in adatom diffusion along the steps and the corners of the islands.

Nucleation and initial growth in the semimetallic homoepitaxial system of Bi on Bi(111)

“…Brune et al 22 found a value of 0.157 eV for Ag on Pt͑111͒, while in the case of Bi on Bi͑111͒ it is 0.135 eV. 8 Additionally, the shape transition occurred in our case is far from the nucleation regime, i.e., at the steady-state regime, which was not the case for Ag/Pt͑111͒, where the shape transition was found just above the nucleation regime.…”

“…The coverage regime we have studied is far below the coalescence regime, since a previous study exhibited no coalescence at 0.5 BL coverage. 8 Thus, the second assumption also holds true. According to Eq.…”

“…7 An understanding of the origin of these properties requires a detailed structural and morphological characterization of the system. Surprisingly Bi-as a covalently bonded semimetalgrows in a bilayer-by-bilayer fashion even at temperatures as low as 80 K. 8 The slow builtup of surface roughness due to a weak step edge barrier can be avoided by growth at higher temperatures, i.e., 300-450 K. Then atomically flat layers with very low defect density can be grown. This is also possible for Bi heteroepitaxy on substrates such as Si.…”

“…This approach was successfully applied in a previous high-resolution LEED analysis and an activation barrier of E d = 0.135 eV for an adatom diffusion in Bi͑111͒ surface was determined. 8 Here a simple approach is used to relate the island density with coverage for a constant deposition tem- Dimensional arguments, based on the theory of random walk, applied to the diffusive motion of adatoms in the nucleation process provides a simple relation between the surface adatom diffusion coefficient and the island number density as 19,20 …”

The growth of bismuth on Bi2Se3 and the stability of the first bilayer

“…Therefore, the growth is not purely SK, and is thus often referred to in the literature as being a quasi bilayer-by-bilayer mode, such as in Refs. [20,49].…”