Tuning metal-insulator transitions in epitaxial V$_2$O$_3$ thin films

TL;DR

This study demonstrates the controlled synthesis of epitaxial V₂O₃ thin films with tunable metal-insulator transitions by adjusting deposition parameters, notably oxygen partial pressure, at lower temperatures than previously reported.

Contribution

It introduces a new low-temperature deposition window for epitaxial V₂O₃ films and links their electronic properties to stoichiometry and strain control.

Findings

Epitaxial V₂O₃ films exhibit a four-order resistance change during the metal-insulator transition.

The transition temperature and magnitude are tunable via oxygen partial pressure during deposition.

Crystallographic structure and surface morphology remain atomically flat despite electronic property variations.

Abstract

We present a study of the synthesis of epitaxial V$_2$O$_3$ films on $c$-plane Al$_2$O$_3$ substrates by reactive dc-magnetron sputtering. The results reveal a temperature window, at substantially lower values than previously reported, wherein epitaxial films can be obtained when deposited on [0001] oriented surfaces. The films display a metal-insulator transition with a change in resistance of up to four orders of magnitude, strongly dependent on the O$_2$ partial pressure during deposition. While the electronic properties of the films show sensitivity to the amount of O$_2$ present during deposition of the films, their crystallographic structure and surface morphology of atomically flat terraced structures with up to micrometer dimensions are maintained. The transition temperature, as well as the scale of the metal-insulator transition, is correlated to the stoichiometry and local strain in the films controllable by the deposition parameters.