Showing papers in "Physical Review in 1991"
Journal Article•
TL;DR: These results show that the bond-length strain in the epitaxial layer appears in the second and higher coordination shells, rather than in the nearest-neighbor bond lengths, which remain the same as in unstrained Ge-Si.
Abstract: The combined techniques of x-ray-absorption fine structure and x-ray diffraction have been used to study the strain and bond distortions in epitaxial Ge-Si on Si(001). In a 31% Ge, 340-\\AA{} pseudomorphic Ge-Si film, the Ge-Ge and Ge-Si first-neighbor bond lengths have been found to be 2.44\\ifmmode\\pm\\else\\textpm\\fi{}0.02 and 2.38\\ifmmode\\pm\\else\\textpm\\fi{}0.02 \\AA{}, respectively. The lattice parameter perpendicular to the Ge-Si/Si(001) interface has been found to be ${\\mathit{a}}_{\\mathrm{\\ensuremath{\\perp}}}$=5.552\\ifmmode\\pm\\else\\textpm\\fi{}0.002 \\AA{}, in agreement with the predictions of macroscopic elastic theory. These results show that the bond-length strain in the epitaxial layer appears in the second and higher coordination shells, rather than in the nearest-neighbor bond lengths, which remain the same as in unstrained Ge-Si. A microscopic model is presented that accounts for these findings.
1 citations
TL;DR: A systematic comparison of the known data on the singlets and triplets arising from sp, sd, sf, and d 9 s configurations with the theory of Houston shows that the theory gives a good account of the deviations from the Lande interval rule which accompany departure from Russell-Saunders coupling.
Abstract: A systematic comparison of the known data on the singlets and triplets arising from sp, sd, sf, and d 9 s configurations with the theory of Houston shows that the theory gives a good account of the deviations from the Lande interval rule which accompany departure from Russell-Saunders coupling. There are numerous significant discrepancies, however. Writing 1 L l and 3L l +1, 3 L l , 3 L l -1 with L = P, D, F, when l = 1, 2, 3 for the term values, we plot as abscissa (3 L l -1 - 3 L l +1)/|3 L l - 1L l | and (3 L l -1 - 3 L l )/(3 L l - 3 L l +1) as ordinate if (3 L l - 1 L l +1) is positive, otherwise the reciprocal of this quantity. Houston’s equations (12) give functional relations between these interval ratios which are compared with the experimental values.
Journal Article•
TL;DR: Results indicate that Sb trimers occupy the threefold atop sites of the Si(111) surface, where each Sb atom is bonded to two Si atoms in a modified bridge configuration.
Abstract: The combined techniques of surface extended x-ray-absorption fine structure (SEXAFS) and high-resolution core and valence photoelectron spectroscopy have been used to study the local bonding structure of the Sb/Si(111) interface. From photoemission, we find that the Sb atoms adsorb in a unique environment that completely saturates the dangling bonds of the Si(111) surface and that completely eliminates the surface components of the Si 2p core-level spectrum. The Sb-induced Si 2p interfacial core level is found to be shifted 0.20\ifmmode\pm\else\textpm\fi{}0.02 eV towards higher binding energy with an intensity that corresponds to the top monolayer of surface atoms. The SEXAFS determination of the absolute surface coordination numbers and bond lengths within the first Sb shell is 2.1\ifmmode\pm\else\textpm\fi{}0.3 Sb atoms at 2.86\ifmmode\pm\else\textpm\fi{}0.02 \AA{} and 2.0\ifmmode\pm\else\textpm\fi{}0.4 Si atoms at 2.66\ifmmode\pm\else\textpm\fi{}0.03 \AA{}. Combined, these results indicate that Sb trimers occupy the threefold atop sites of the Si(111) surface, where each Sb atom is bonded to two Si atoms in a modified bridge configuration.