Surface core-level shifts of GaAs(100)(2x4) from first principles
2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 11Article in journal (Refereed) Published
First-principles calculations show that measured surface core-level shifts (SCLSs) of the GaAs(100)(2x4) surfaces can be described within the initial state effects. The calculated As 3d and Ga 3d SCLSs for the beta 2 and alpha 2 reconstructions of the GaAs(100)(2x4) surfaces are in reasonable agreement with recent measurements. In particular, the results confirm that both the lower and the higher binding energy SCLSs, relative to the bulk emission in the As 3d photoelectron spectra, are intrinsic properties of the GaAs(100)(2x4) surfaces. The most positive and most negative As shifts are attributed to the third layer As atoms, which differs from the previous intuitive suggestions. In general, calculations show that significant SCLSs arise from deep layers, and that there are more than two SCLSs. Our previously measured As 3d spectra are fitted afresh using the calculated SCLSs. The intensity ratios of the SCLSs, obtained from the fits, show that as the heating temperature of the GaAs(100)(2x4) surface is increased gradually, the area of the alpha 2 reconstruction increases on the surface, but the beta 2 phase remains within the whole temperature range, in agreement with previous experimental findings. Our results show that the combination of the experimental and theoretical results is a prerequisite for the accurate analysis of the SCLSs of the complex reconstructed surfaces.
Place, publisher, year, edition, pages
2007. Vol. 76, no 11
scanning-tunneling-microscopy, total-energy calculations, augmented-wave method, binding-energy, electronic-structure, molecular-dynamics, atomic-structure, charge-transfer, chemical-shift, basis-set
IdentifiersURN: urn:nbn:se:kth:diva-16985DOI: 10.1103/PhysRevB.76.115334ISI: 000249786400088ScopusID: 2-s2.0-34848887170OAI: oai:DiVA.org:kth-16985DiVA: diva2:335028
QC 201005252010-08-052010-08-05Bibliographically approved