Local electronic structure of doping defects on Tl/Si(111)1x1

Abstract

The Tl/Si(111)1 × 1 surface is a representative of a 2D layer with Rashba-type spin-split electronic bands. To utilize the spin polarization, doping of the system should be understood on atomic level. We present a study of two types of atomic defects predicted to dope the considered electronic system – Si-induced vacancies and defects associated with the presence of extra Tl atoms. Structural calculations based on density functional theory (DFT) confirm the stability of the proposed defect structure consisting of an extra Si atom and missing seven Tl atoms as proposed in an earlier experimental study. The calculated spatial charge distributions indicate an enhancement of the charge around the extra Si atom, which correctly reproduces topographies of the corresponding scanning tunneling microscopy images while the calculated local densities of states of this system explain obtained scanning tunneling spectra. The DFT structural calculations let us determine the atomic structure of the defect caused by the presence of an extra Tl atom. The calculated spatial charge distributions show a ring-like feature around the extra Tl atom. The obtained results indicate a charge transfer from the central extra Tl atom to its vicinity in the agreement with earlier photoemission measurements.

Stability of Partially Fluorinated Phthalocyanine Monolayers: Influence of Hydrogen Bonding Revisited

“…The pseudomorphicity allows the easiest commensuration of the surface periodicity with that of the molecular layer compared to other reconstructed silicon surfaces. Electronic states with giant spin–orbit-induced spin splitting ,, of the Si(111)-Tl 1 × 1 can be tuned by surface defects , which brings possibility of tuning the electronic states by adsorbed molecules as well.…”