Atomic layer deposition and characterization of vanadium oxide thin films

Abstract

In this study, VO_x films were grown by atomic layer deposition (ALD) using V(NEtMe)₄ as the vanadium precursor and either ozone or water as the oxygen source. V(NEtMe)₄ is liquid at room temperature and shows good evaporation properties. The growth was investigated at deposition temperatures from as low as 75 °C, up to 250 °C. When using water as the oxygen source, a region of constant growth rate (ca. 0.8 Å/cycle) was observed between 125 and 200 °C, with the ozone process the growth rate was significantly lower (0.31–0.34 Å/cycle). The effect of the process conditions and post-deposition annealing on the film structure was investigated. By varying the atmosphere under which the films were annealed, it was possible to preferably form either VO₂ or V₂O₅. Atomic force microscopy revealed that the films were smooth (rms < 0.5 nm) and uniform. The composition and stoichiometry of the films were determined by X-ray photoelectron spectroscopy. Conformal deposition was achieved in demanding high aspect ratio structure.