title: Tunneling spectroscopy of close-spaced dangling-bond pairs in Si(001):H.
abstract: We present a combined experimental and theoretical study of the electronic properties of close-spaced dangling-bond (DB) pairs in a hydrogen-passivated Si(001):H p-doped surface. Two types of DB pairs are considered, called "cross" and "line" structures. Our scanning tunneling spectroscopy (STS) data show that, although the spectra taken over different DBs in each pair exhibit a remarkable resemblance, they appear shifted by a constant energy that depends on the DB-pair type. This spontaneous asymmetry persists after repeated STS measurements. By comparison with density functional theory (DFT) calculations, we demonstrate that the magnitude of this shift and the relative position of the STS peaks can be explained by distinct charge states for each DB in the pair. We also explain how the charge state is modified by the presence of the scanning tunneling microscopy (STM) tip and the applied bias. Our results indicate that, using the STM tip, it is possible to control the charge state of individual DBs in complex structures, even if they are in close proximity. This observation might have important consequences for the design of electronic circuits and logic gates based on DBs in passivated silicon surfaces.
authors.affiliation: Centro de Física de Materiales CSIC-UPV/EHU, Paseo Manual de Lardizabal 5, E-20018, Donostia-San Sebastián, Spain.
authors.forename: Mads
authors.initials: M
authors.lastname: Engelund
authors.affiliation: Center for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, PL-30-348, Krakow, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Zuzak
authors.affiliation: Center for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, PL-30-348, Krakow, Poland.
authors.forename: Szymon
authors.initials: S
authors.lastname: Godlewski
authors.affiliation: Center for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, PL-30-348, Krakow, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Kolmer
authors.affiliation: Donostia International Physics Center, Paseo Manual de Lardizabal 4, 20018, Donostia-San Sebastián, Spain.|IKERBASQUE, Basque Foundation for Science, E-48013, Bilbao, Spain.
authors.forename: Thomas
authors.initials: T
authors.lastname: Frederiksen
authors.affiliation: Donostia International Physics Center, Paseo Manual de Lardizabal 4, 20018, Donostia-San Sebastián, Spain.|IKERBASQUE, Basque Foundation for Science, E-48013, Bilbao, Spain.
authors.forename: Aran
authors.initials: A
authors.lastname: García-Lekue
authors.affiliation: Centro de Física de Materiales CSIC-UPV/EHU, Paseo Manual de Lardizabal 5, E-20018, Donostia-San Sebastián, Spain.|Donostia International Physics Center, Paseo Manual de Lardizabal 4, 20018, Donostia-San Sebastián, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sánchez-Portal
authors.affiliation: Center for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, PL-30-348, Krakow, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Szymonski