The defect structures which formed on (001) surfaces that were heated to various temperatures were studied by means of high-resolution spot profile analysis low-energy electron diffraction and scanning tunnelling microscopy. By using the latter technique, tetragonal pyramids were observed after annealing the surface at 1400K. These were formed by a thermal etching process that removed Si from the surface. With increasing slope of the pyramid planes, there was a transformation from monatomic to DB double steps. In the case of the latter, dimer rows of the 2 x 1 reconstruction extended perpendicularly to the step edges. Pyramid planes with DB double steps, that were rotated by 90, transformed into each other via the formation of single-step planes. At an annealing temperature of 1600K, very flat surfaces with only monatomic steps were formed. A profile analysis of the specular and half-order beams of the 2-domain (001) (2 x 1) low-energy electron diffraction pattern was performed. This revealed step structures which were identical to the results of real-space scanning tunnelling microscopic studies.

A.W.Munz, W.Weiss, W.Göpel: Journal of Physics - Condensed Matter, 1995, 7[27], 5313-26