title: Scanning tunneling microscopy and surface simulation of zinc-blende GaN(001) intrinsic 4x reconstruction: linear gallium tetramers?
abstract: Scanning tunneling microscopy images confirm electron diffraction studies that the zinc-blende GaN(001)-4x reconstruction consists of rows aligned along [110] with a spacing along [110] of 4a. Dual-bias imaging shows a 180 degree shift of the corrugation maximum position between the profiles of empty and occupied states, in agreement with surface simulations based on the 4 x 1 linear tetramer model of Neugebauer et al. [Phys. Rev. Lett. 80, 3097 (1998)]. Electronic structure calculations predict a surface band gap of 1.1 eV, close to the measured value of 1.14 eV and the previously predicted value (1.2 eV). Despite the successes of this model, high-resolution images reveal an unexpected 3x periodicity (not seen in diffraction) along the [110] row direction, indicating the need for a 4 x 3 model, and putting into question the existence of linear Ga tetramers.
authors.affiliation: Condensed Matter and Surface Science Program, Department of Physics and Astronomy, Ohio University, Athens, Ohio 45701, USA.
authors.forename: Hamad A H
authors.initials: HA
authors.lastname: Al-Brithen
authors.forename: Rong
authors.initials: R
authors.lastname: Yang
authors.forename: Muhammad B
authors.initials: MB
authors.lastname: Haider
authors.forename: Costel
authors.initials: C
authors.lastname: Constantin
authors.forename: Erdong
authors.initials: E
authors.lastname: Lu
authors.forename: Arthur R
authors.initials: AR
authors.lastname: Smith
authors.forename: Nancy
authors.initials: N
authors.lastname: Sandler
authors.forename: Pablo
authors.initials: P
authors.lastname: Ordejón