Amorphous vanadium dioxide (VO2) films deposited by atomic layer deposition (ALD) were crystallized with an ex situ anneal at 660-670 degC for 1-2 hours under a low oxygen pressure (10−4 to 10−5 Torr). Under these conditions the crystalline VO2 phase was maintained, while formation of the V2O5 phase was suppressed. Electrical transition from the insulator to the metallic phase was observed in the 37-60 degC range, with a RON/ROFF ratio of up to about 750 and critical transition temperature of 7-10 degC. Electric field applied across two-terminal device structures induced a reversible phase change, with a room temperature transition field of about 25 kV/cm in the VO2 sample processed with the 2 hr long anneal. Both the width and slope of the field induced MIT hysteresis were dependent upon the VO2 crystalline quality.
@article{arxiv.1602.06340,
title = {Temperature and Electric Field Induced Metal-Insulator Transition in Atomic Layer Deposited Vanadium Dioxide Thin Films},
author = {Marko J. Tadjer and Virginia D. Wheeler and Brian P. Downey and Zachary R. Robinson and David J. Meyer and Charles R. Eddy, and Fritz J. Kub},
journal= {arXiv preprint arXiv:1602.06340},
year = {2017}
}