Ordering of subsurface interstitial atoms in the Ge(113) surface studied by SPA-LEED

The surface order of the reconstructed Ge(113)-(3 x 2) phase was investigated by SPA-LEED (Spot Profile Analysis Low Energy Electron Diffraction). The LEED pattern exhibits very sharp (3 x 1) spots and broadened (3 x 2) spots which can be traced back to a disordered phase of interstitial atoms. At temperatures below 370 K, the (3 x 2) spots are split in the [1 (1) over bar 0] direction. A quantitative determination of the domain size distributions with the domain matrix method reveals that the split profiles can be explained with a non-geometrical distribution of (3 x 2) domains separated by antiphase domain boundaries. This may indicate a relief of surface stress at antiphase domain boundaries in the [1 (1) over bar 0] direction. Thereby, a fraction of 70 +/- 13% of the surface is covered with (3 x 2) domains, while the remaining part consists of domain boundaries and (3 x 1) domains. For temperatures above 370 K, a splitting of the (3 x 2) spots is not observed, and the domain size distributions are geometric. (C) 1999 Elsevier Science B.V. All rights reserved.