Atomic layer deposition of vanadium oxide thin films from tetrakis(dimethylamino)vanadium precursor

Atomic layer deposition (ALD) of vanadium oxide (VO x ) thin films, using tetrakis(dimethylamino)vanadium as the vanadium precursor, is comprehensively reported in this work. The vanadium precursor is highly volatile and can be used at room temperature for deposition. Either H 2 O or O 3 can be used as the coreactant for depositing VO x at 50–200 °C. However, partial precursor decomposition is suggested for the deposition temperature higher than 160 °C. The as-deposited VO x films are pure, smooth, and amorphous, and can be crystallized into monoclinic VO 2 phase by postdeposition annealing under N 2 ambient. The minimum annealing temperature for film to crystallize is found, by in situ high-temperature X-ray diffraction experiments, at around 550–600 °C. In situ quartz crystal microbalance experiments are performed to further analyze the surface reaction mechanism involved in this ALD process.