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

TL;DR

This study demonstrates that atomic layer deposited VO₂ thin films undergo a reversible metal-insulator transition induced by temperature and electric field, with properties influenced by the film's crystalline quality.

Contribution

It reports the fabrication and characterization of crystalline VO₂ films via ALD and annealing, showing electric field-induced phase change at room temperature.

Findings

Electrical MIT observed between 37-60°C with high R_ON/R_OFF ratio.

Electric field of about 25 kV/cm induces reversible phase change.

Crystalline quality affects the hysteresis width and slope of the MIT.

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.