Postdeposition annealing on VO₂ films for resistive random-access memory selection devices

In this study, VO₂ films were deposited by thermal atomic layer deposition with vanadium oxytriisopropoxide as a vanadium precursor and deionized water as a reactant. Postdeposition annealing was performed in order to enhance the crystallinity of VO₂ films. X-ray diffraction, scanning electron microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, and transmission electron microscopy were used to characterize the physical and chemical properties of the as-deposited and annealed VO₂ films. The results indicated that postdeposition annealing enhanced the crystallinity of the VO₂ films and increased the area ratio of V⁴⁺. Finally, the electrical properties of the VO₂ films were analyzed using a semiconductor parameter analyzer. The I_on/I_off ratio increased from 10² to 10⁴ during postdeposition annealing at 450 °C. There were also significant increases in the hysteresis window.