Vibration-Driven Self-Doping of Dangling-Bond Wires on Si(553)-Au Surfaces

Abstract

Density-functional theory is used to explore the Si(553)-Au surface dynamics. Our study (i) reveals a complex two-stage order-disorder phase transition where with rising temperature first the ×3 order along the Si step edges and, subsequently, the ×2 order of the Au chains is lost, (ii) identifies the transient modification of the electron chemical potential during soft Au chain vibrations as instrumental for disorder at the step edge, and (iii) shows that the transition leads to a self-doping of the Si dangling-bond wire at the step edge. The calculations are corroborated by Raman measurements of surface phonon modes and explain previous electron diffraction, scanning tunneling microscopy, and surface transport data.

Free and defect-bound (bi)polarons inLiNbO3: Atomic structure and spectroscopic signatures fromab initiocalculations

“…This is in reasonable agreement with the experimentally observed value of 0.27 eV [63], keeping in mind that we neglect barrier-lowering effects of phonons and entropy in this estimate. A recent study [64] showed that these effects are small but not negligible in the case of Au nanowires on a Si step.…”

Lack of temperature dependence for the filling of the metallic-like bands in Si(553)-Au

“…In the order-disorder phase-transition model of Ref. 8 , a charge transfer from the step-edge to the metallic-like bands is expected. Such change in carrier-density of the step-edge can then be discussed to have an effect on the dimerization of the Au-ladder 22 and, therefore could act as an explanation alternative to the partial-gapping of the Au-bands advocated by us in Ref.…”

“…The Si(553)-Au surface system is a prototype example for a low-dimensional surface system 1,2 . A structural model for this surface system was refined by experiment 3,4 and density functional theory (DFT) 5,6 with details still ongoing 7,8 . Fig.…”

Z3 Charge Density Wave of Silicon Atomic Chains on a Vicinal Silicon Surface

“… 13 − 15 , 21 , 22 , 25 − 28 The recent electron diffraction study revealed that the ×2 structure along the terrace Au chains has a static structural distortion without a drastic temperature dependence, 25 , 27 which is consistently supported by the recent density functional theory (DFT) calculations. 15 However, the origin of the temperature-induced ×3 ordering along Si step-edge chains 21 , 29 is still unclear with the suggestions of the electronic/structural instability 15 , 26 , 28 and the antiferromagnetic spin ordering on Si dangling bonds. 13 On the basis of the latter, even a quantum spin liquid phase was suggested.…”