Optimisation of anatase TiO2 thin film growth on LaAlO3(0 0 1) using pulsed laser deposition

Abstract

Optimisation of epitaxial anatase TiO2 thin films grown on LaAlO3(0 0 1) substrates was performed using ultra-high vacuum based pulsed laser deposition (PLD) and studied by in-situ reflection high-energy electron diffraction (RHEED). In addition, ex-situ X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning transmission electron microscopy (STEM) were performed to characterise the bulk properties of these thin films. The deposited TiO2 thin film is demonstrated to have anatase phase and bonded directly to the LaAlO3(0 0 1) substrate. In a separate ultra-high vacuum system low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) measurements were performed and a well-ordered two-domain (1×4) and (4×1) reconstruction of anatase surface was observed. Analysis of the STM measurements indicates the coexistence of atomic steps of both 2.5Å and 5.0Å, confirming the existence of two TiO2 domains. The atomic resolution STEM images reveal that the TiO2/LaAlO3 interface to be terminated with LaO layer and that the anatase-TiO2 reconstruction was found to be stable during the film growth.