Electrical Oscillation in Pt/VO2 Bilayer Strips

TL;DR

This paper demonstrates stable electrical oscillations in Pt/VO2 bilayer strips driven mainly by Joule heating in the Pt layer, with oscillation frequency affected by bias current and device size, offering new insights into VO2-based oscillator mechanisms.

Contribution

It introduces a new mechanism for VO2 oscillations driven by Joule heating in a Pt overlayer, contrasting with previous electrically triggered models.

Findings

Oscillation frequency increases with bias current.

Oscillation frequency increases with decreasing device size.

Joule heating in Pt dominates the oscillation mechanism.

Abstract

We report on the observation of stable electrical oscillation in Pt/VO2 bilayer strips, in which the Pt overlayer serves the dual purposes of heating up the VO2 and weakening the electric field in the VO2 layer. Systematic measurements in an ultrahigh vacuum nanoprobe system show that the oscillation frequency increases with the bias current and/or with decreasing device dimension. In contrast to most VO2-based oscillators reported to date, which are electrically triggered, current-induced Joule heating in the Pt overlayer is found to play a dominant role in the generation of oscillation in Pt/VO2 bilayers. A simple model involving thermally triggered transition of VO2 on a heat sink is able to account for the experimental observations. The results in this work provide an alternative view of the triggering mechanism in VO2-based oscillators.