Core-level spectroscopy of the clean Si(001) surface: Charge transfer within asymmetric dimers of the 2×1 andc(4×2) reconstructions

Abstract

Extremely well-resolved Si 2p core-level spectra have been obtained from the clean Si(001) surface. Spectra from the cold c(4x2) and the RT 2x 1 surfaces are very similar, implying that the local structure of the two reconstructions is the same. Shifted components originating from both up and down atoms of asymmetric dimers, as well as second-layer atoms, are identified. The split of -0.55 eV between the two dimer-atom components points to a substantial charge transfer within the dimers. We find no support for the recently proposed crystal-field splitting of the surface components.

Identification of the basic structure of the Ag/Si(111)-(6×1)surface: Observation of a low-temperaturec(12×2)phase

“…Such results for Si 2p core-level spectra from different surface structures, are also observed on a clean Si͑001͒ surface. 26 That is, the room temperature Si͑001͒-(2ϫ1) and low-temperature c(4ϫ2) phases show very similar Si 2p spectra, and they have surface components with the same energy shifts. 26 In this case, the similarity of the Si 2p corelevel spectra indicates that the local surface structure is the same for the two phases, and that the room-temperature (2 ϫ1) phase results from the dynamical flipping of the asymmetric dimers 27 at a high frequency.…”

“…26 That is, the room temperature Si͑001͒-(2ϫ1) and low-temperature c(4ϫ2) phases show very similar Si 2p spectra, and they have surface components with the same energy shifts. 26 In this case, the similarity of the Si 2p corelevel spectra indicates that the local surface structure is the same for the two phases, and that the room-temperature (2 ϫ1) phase results from the dynamical flipping of the asymmetric dimers 27 at a high frequency. Since the translational vectors of the c(12ϫ2) unit cell are twice as long compared to the (6ϫ1)-reconstructed structure, there should be an alternate displacement of Ag atoms and/or the site of the toplayer Si atoms along both translational vectors.…”

Effect of the cluster size in modeling the H2 desorption and dissociative adsorption on Si(001)

“…Direct evidence for the buckling comes from low-temperature STM images 27 and structure determinations by LEED 44 . Furthermore, observed core-level shifts 45 are inconsistent with symmetric surface dimers, but can be explained by buckled dimers 46 . The buckled surface reconstruction has gained further support by the good agreement between the measured dispersion of surface band states 47 with calculations using the GW approximation 48 .…”

Surface core-level shifts on clean Si(001) and Ge(001) studied with photoelectron spectroscopy and density functional theory calculations

“…The generally accepted decomposition, originating from Ref. 7, consists of five shifted components in addition to a bulk component. A decomposition where these five surface shifted components and a bulk component are used is shown in Fig.…”

“…Even though the atomic origins are being debated, there is an overall agreement regarding the energy position of the major components in the Si 2p spectra. [6][7][8][9][10] The components of the Ge 3d spectrum from Ge͑001͒ are less well established [11][12][13][14][15] due to the lack of pronounced features in the spectra.…”