Persistent insulator-to-metal transition of a VO sub(2) thin film induced by soft X-ray irradiation

• Published in: Japanese Journal of Applied Physics Vol. 53; no. 5S1; pp. 05FB09 - 1-05FB09-4
• Main Authors: Muraoka, Yuji, Nagao, Hiroki, Katayama, Shinsuke, Wakita, Takanori, Hirai, Masaaki, Yokoya, Takayoshi, Kumigashira, Hiroshi, Oshima, Masaharu
• Format: Journal Article
• Language: English
• Published: 01.01.2014
• Subjects: Band spectra; Density of states; Desorption; Irradiation; Oxygen consumption; Soft x-rays; Spectra; Thin films; Vanadium oxides
• ISSN: 0021-4922; 1347-4065
• DOI: 10.7567/JJAP.53.05FB09

We present a persistent soft-X-ray-induced insulator-to-metal transition at room temperature for VO sub(2) thin films. Continuous soft X-ray irradiation renders the insulating electronic state metallic in the VO sub(2) thin films, which has been found by photoemission spectroscopy measurement. The observed transition is irreversible and the metallic state persists when soft X-ray irradiation is stopped. The analysis of valence band spectra reveals that the density of states (DOS) of the V 3d band increases with irradiation time, while the DOS of the O 2p band decreases. We propose a simple model where the persistent insulator-to-metal transition is driven by oxygen desorption from VO sub(2) thin films under soft X-ray irradiation. The present results will help in developing a new route for controlling the phase transition of VO sub(2) by light.