Thermally Annealed Sub-Monolayers of AlF3 on Cu(100): An STM and XPS Study

Abstract

A steady and durable transition from rough and randomly oriented 2D aluminum fluoride clusters to ultra-thin films with defined arrangement is here reported. Scanning tunneling microscopy images show that the material deposited on top of Cu(100) reveals a smooth surface with a preferential arrangement and a transition in the morphology of the islands after performing a post-deposition annealing treatment at 575 K. X-ray photoelectron spectroscopy shows that the chemical environment of fluoride atoms remains unaltered after performing annealing treatments at this temperature. However, the tunneling voltage used to acquire STM images of the films changes from typical insulator values to metallic-like ones after annealing. These results suggest an important change in the local density of states of the aluminum fluoride islands after the post-deposition annealing treatment.