Process Study and Characterization of VO2 Thin Films Synthesized by ALD Using TEMAV and O3 Precursors

Vanadium oxide (VO2) thin films were prepared by atomic layer deposition using TEMAV (tetrakis[ethylmethylamido]vanadium) precursor and ozone as the reactant gas. Study on the precursor as well as oxidizer doses and temperature dependence showed none of them exhibited the characteristics of ideal ALD. The VO2 phase formation pathways, its process window, and surface roughness are found to be sensitive to the anneal conditions applied and the substrate used. The VO2 morphology on Al2O3 was found to be island-like whereas on Si/SiO2 either a nano particle formation or a continuous film was obtained. GIXRD demonstrated the VO2 crystallization window to be very narrow on Al2O3 and thick SiO2 while a relatively broad window is obtained on 1 nm SiO2. A reversible change in sheet resistance was measured with more than three orders of magnitude for a 30 nm film.