Effect of Thermal Annealing on Structural Properties, Morphologies and Electrical Properties of TiO2 Thin Films Grown by MOCVD

Abstract

TiO2 thin films, were deposited on Si(100) and Si(111) substrates by metalorganic chemical vapor deposition at 500 °C, and have been annealed for 2 min, 30 min and 10 hours at the temperature from 600 °C to 900 °C, in oxygen and air flow, respectively. XRD and atomic force microscopy characterized the structural properties and surface morphologies of the films. As-deposited films show anatase polycrystalline structure with a surface morphology of regular rectangled grains with distinct boundaries. Rutile phase formed for films annealed above 600 °C, and pure rutile polycrystalline films with (110) orientation can be obtained after annealing under adequate conditions. Rutile annealed films exhibit a surface morphology of equiaxed grains without distinct boundaries. The effects of substrate orientation, annealing time and atmosphere on the structure and surface morphology of films have also been studied. Capacitance-Voltage measurements have been performed for films deposited on Si(100) before and after annealing. The dielectric properties of TiO2 films were greatly improved by thermal annealing above 600 °C in oxygen.