title: Layer-by-layer growth of sodium chloride overlayers on an Fe(001)-p(1 × 1)O surface.
abstract: Ultra-thin NaCl films epitaxially grown on an Fe(001)-p(1 × 1)O surface have been investigated in ultra-high vacuum by non-contact atomic force microscopy and low energy electron diffraction. It has been found that at temperatures below 145 °C NaCl initially grows as monoatomic thick islands on substrate terraces, while at temperatures above 175 °C biatomic thick islands are also formed at substrate step edges. Both types of islands have the same Fe(001)-O[100] [parallel] NaCl(001)[110] orientation, leading to a (4 × 4) superstructure, where the NaCl unit cell is oriented at 45° with respect to the substrate. Interestingly, no c(2 × 2) superstructure with the NaCl unit cell oriented at 0° has been observed. The oxygen on the iron surface promotes layer-by-layer growth, resulting in atomically flat films with 40-60 nm wide terraces at coverages ranging from 0.75 to 12 ML. Such NaCl films are of much higher quality than MgO films grown on Fe(001) and Fe(001)-p(1 × 1)O surfaces and represent a unique epitaxial system of an alkali halide on a pure metallic substrate. The reduced number of defects and the layer-by-layer mode of growth make this system very attractive for applications where an atomically defined tunnel barrier is required to control the properties of a device.
authors.affiliation: Physics Department, McGill University, 3600 University Street, Montreal, QC H3A 2T8, Canada. antoni.tekiel@mail.mcgill.ca
authors.forename: Antoni
authors.initials: A
authors.lastname: Tekiel
authors.forename: Jessica
authors.initials: J
authors.lastname: Topple
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Miyahara
authors.forename: Peter
authors.initials: P
authors.lastname: Grütter