Transport behavior and electronic structure of phase pure VO2 thin films grown on c-plane sapphire under different O2 partial pressure

TL;DR

This study investigates how varying oxygen partial pressure during growth affects the structure and transport properties of phase pure VO2 thin films on sapphire substrates.

Contribution

It provides new insights into the relationship between oxygen pressure, lattice parameters, and metal-semiconductor transition in VO2 thin films.

Findings

Increased O2 flow reduces the [010] lattice parameter.

Distinct changes in MST and transport behaviors occur with oxygen pressure.

Valence state of vanadium remains unchanged despite different oxygen pressures.

Abstract

We grew highly textured phase pure VO2 thin films on c-plane Al2O3 substrates with different oxygen partial pressure. X-ray absorption and photoemission spectroscopy confirm the identical valence state of vanadium ions despite the different oxygen pressure during the deposition. As the O2 flow rate increases, the [010] lattice parameter for monoclinic VO2 was reduced and coincidently distinctive changes in the metal- semiconductor transition (MST) and transport behaviors were observed despite the identical valence state of vanadium in these samples. We discuss the effect of the oxygen partial pressure on the monoclinic structure and electronic structure of VO2, and consequently the MST.