Temperature and Electric Field Induced Metal-Insulator Transition in Atomic Layer Deposited Vanadium Dioxide Thin Films

Abstract: Amorphous vanadium dioxide (VO${2}$) films deposited by atomic layer deposition (ALD) were crystallized with an ex situ anneal at 660-670 ${\deg}$C for 1-2 hours under a low oxygen pressure (10$^{-4}$ to 10$^{-5}$ Torr). Under these conditions the crystalline VO${2}$ phase was maintained, while formation of the V${2}$O${5}$ phase was suppressed. Electrical transition from the insulator to the metallic phase was observed in the 37-60 ${\deg}$C range, with a R${ON}$/R${OFF}$ ratio of up to about 750 and critical transition temperature of 7-10 ${\deg}$C. 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 VO${2}$ sample processed with the 2 hr long anneal. Both the width and slope of the field induced MIT hysteresis were dependent upon the VO${2}$ crystalline quality.