MIT characteristic of VO₂ thin film deposited by ALD using vanadium oxytriisopropoxide precursor and H₂O reactant

Abstract

VO₂ is an attractive candidate as a transition metal oxide switching material as a selection device for reduction of sneak-path current. We demonstrate deposition of nanoscale VO₂ thin films via thermal atomic layer deposition (ALD) with H₂O reactant. Using this method, we demonstrate VO₂ thin films with high-quality characteristics, including crystallinity, reproducibility using X-ray diffraction, and X-ray photoelectron spectroscopy measurement. We also present a method that can increase uniformity and thin film quality by splitting the pulse cycle into two using scanning electron microscope measurement. We demonstrate an ON / OFF ratio of about 40, which is caused by metal insulator transition (MIT) of VO₂ thin film. ALD-deposited VO₂ films with high film uniformity can be applied to next-generation nonvolatile memory devices with high density due to their metal-insulator transition characteristic with high current density, fast switching speed, and high ON / OFF ratio.