title: New insights on atomic-resolution frequency-modulation Kelvin-probe force-microscopy imaging of semiconductors.
abstract: We present dynamic force-microscopy experiments and first-principles simulations that contribute to clarify the origin of atomic-scale contrast in Kelvin-probe force-microscopy (KPFM) images of semiconductor surfaces. By combining KPFM and bias-spectroscopy imaging with force and bias-distance spectroscopy, we show a significant drop of the local contact potential difference (LCPD) that correlates with the development of the tip-surface interatomic forces over distinct atomic positions. We suggest that variations of this drop in the LCPD over the different atomic sites are responsible for the atomic contrast in both KPFM and bias-spectroscopy imaging. Our simulations point towards a relation of this drop in the LCPD to variations of the surface local electronic structure due to a charge polarization induced by the tip-surface interatomic interaction.
authors.affiliation: Helmholtz Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, Berlin, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Sadewasser
authors.forename: Pavel
authors.initials: P
authors.lastname: Jelinek
authors.forename: Chung-Kai
authors.initials: CK
authors.lastname: Fang
authors.forename: Oscar
authors.initials: O
authors.lastname: Custance
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Yamada
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Abe
authors.forename: Seizo
authors.initials: S
authors.lastname: Morita