Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 24: Semiconductor Substrates: Epitaxy and Growth
O 24.2: Vortrag
Dienstag, 27. März 2007, 11:30–11:45, H39
Lattice accommodation by a periodic array of interfacial misfit dislocations in Bi(111)/Si(001) heteroepitaxy — •Giriraj Jnawali, Hichen Hattab, Frank M. zu Heringdorf, Boris Krenzer, and Michael Horn von Hoegen — Fachbereich Physik, Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg, Germany
Ultra-smooth Bi(111) films with very low defect density could be grown on Si(001) following a recipe published by Jnawali et al.1. Surprisingly the hexagonal Bi(111) lattice fits quite well with the rectangular Si(001) lattice with a low misfit in both the [110] and [110] directions. A remaining lattice mismatch of 2.3 % is accommodated by the formation of a periodic array of misfit dislocations at the interface. The dislocations are generated during annealing of a 6 nm thick Bi(111) film from 150 K to 450 K while the film relaxes. The periodic one dimensional dislocation array is observed via its strain fields and the accompanied surface undulation by spot splitting in high resolution LEED (SPA-LEED). From the satellite spot intensity at different scattering phases, the amplitude Δh = 0.66 Å and the average length Γ = 200 Å of the wave-like periodic surface undulation is determined. Comparing these results with a continuum theory for elastic distortion by Springholz et al.2 we conclude that the misfit dislocation at the interface is a full-dislocation with Burgers vector of b = 1/2[110] defined by the surface lattice constant of the Si(001) surface.
[1] G. Jnawali, H. Hattab, B. Krenzer, and M. Horn von Hoegen, Phys. Rev. B, 74, 195340 (2006).
[2] G. Springholz, Appl. Surf. Sci. 112, 12 (1997).