Ehrlich Schwöbel barrier

Ehrlich Schwöbel barrier at the level limit

The Ehrlich-Schwöbel-Barrier or Schwöbel-Barrier is a potential barrier that forms on the step edge of multilayer surfaces . It was named after Gert Ehrlich , who first observed it with a field ion microscope in 1966 , and Richard L. Schwoebel (1931–2012), who described it theoretically.

If the energy required to overcome the diffusion barrier and the activation energy to overcome the potential wall is at the edge of the step, then the Ehrlich-Schwöbel barrier applies . It depends on the material and the crystal plane. The bond is stronger below the edge. ${\displaystyle E_{\mathrm {diff} }}$ ${\displaystyle E_{\mathrm {B} }}$ ${\displaystyle E_{\mathrm {ES} }=E_{\mathrm {B} }-E_{\mathrm {diff} }}$

If or then, the Schwöbel barrier inhibits diffusion between the layers and thus influences the growth and formation of islands. In this case the particles are reflected off it . Also from the side of the potential well, no atoms can diffuse over the edge of the step. If a Schwöbel barrier forms at the border of the Adatom Islands after uniform nucleation, 3D growth without diffusion occurs. The island areas are then Poisson-distributed depending on their height . ${\displaystyle E_{\mathrm {ES} }\gg E_{\mathrm {diff} }}$ ${\displaystyle E_{\mathrm {diff} }<kT<E_{\mathrm {B} }}$

literature

• Stefan Kowarik, Katharina Broch and Frank Schreiber: Watching the growth . In: Physics Journal . tape 13 , no. 12 , 2014, p. 33–39 ( uni-tuebingen.de [PDF]).
• Z. Chromcova, MC Tringides, Z. Chvoj: Nucleation on a stepped surface with an Ehrlich – Schwöbel barrier . In: Journal of Physics: Condensed Matter . tape 25 , no. 26 , July 3, 2013, p. 265003 , doi : 10.1088 / 0953-8984 / 25/26/265003 .
• Chuan-Fu Lin, Ajmi BH Hammouda, Hung-Chih Kan, NC Bartelt, RJ Phaneuf: Directing self-assembly of nanostructures kinetically: Patterning and the Ehrlich-Schwoebel barrier . In: Physical Review B . tape 85 , no. 8 , February 13, 2012, p. 085421 , doi : 10.1103 / PhysRevB.85.085421 .
• SJ Liu, Hanchen Huang, CH Woo: Schwoebel-Ehrlich barrier: from two to three dimensions . In: Applied Physics Letters . tape 80 , no. 18 , May 6, 2002, pp. 3295-3297 , doi : 10.1063 / 1.1475774 .

Individual evidence

1. ↑ Gert Ehrlich, FG Hudda: Atomic View of Surface Self ‐ Diffusion: Tungsten on Tungsten . In: The Journal of Chemical Physics . tape 44 , no. 3 , February 1, 1966, p. 1039-1049 , doi : 10.1063 / 1.1726787 .
2. ↑ Richard L. Schwoebel, Edward J. Shipsey: Step Motion on Crystal Surfaces . In: Journal of Applied Physics . tape 37 , no. 10 , 1966, pp. 3682-3686 , doi : 10.1063 / 1.1707904 (English).
3. ↑ Richard L. Schwoebel: Step Motion on Crystal Surfaces. II . In: Journal of Applied Physics . tape 40 , no. 2 , February 1, 1969, p. 614-618 , doi : 10.1063 / 1.1657442 .
4. ↑ Olaf Kurtz: The growth of rhodium on a graphite (0001) and a rhenium (0001) surface . 1999 ( PDF [accessed July 21, 2015]).