Defect structures, formed on Si(001) surfaces heated to various temperatures, were studied using a high-resolution spot profile analysis low-energy electron diffraction system and a scanning tunnelling microscope. Using scanning tunnelling microscopy, tetragonal pyramids were observed after annealing the surface to 1400K. These were formed by a thermal etching process that removed silicon from the surface. With increasing slope of the pyramid planes, a transformation from monatomic to DB double steps was observed. For the latter, dimer rows of the (2 x 1) reconstruction extended perpendicular to the step edges. Pyramid planes with DB double steps that were rotated by 90° transformed into each other by the formation of single-stepped planes. For annealing temperatures of 1600K, very flat surfaces with monatomic steps alone were formed. A profile analysis of the specular and half-order beams of the 2-domain Si(001) (2 x 1) low-energy electron diffraction pattern was performed after the same preparation procedures were applied to the samples. This analysis led to step structures that were identical with the results of real-space scanning tunnelling microscopic studies.

Thermal Etching Defect Structures on Si(001) - a Comparative Study with High-Resolution Low-Energy Electron Diffraction and Scanning Tunnelling Microscopy. A.W.Munz, W.Weiss, W.Gopel: Journal of Physics - Condensed Matter, 1995, 7[27], 5313-26