Optical Properties of Vanadium Pentoxide Deposited by ALD

Abstract

Nanostructures of V₂O₅ find important technological applications in optics, catalysis, and lithium ion batteries. Their optical properties and surface roughness are important parameters in these respects. Here we report on atomic layer deposition (ALD) of V₂O₅ using the β-diketonate VO­(thd)₂ and ozone as precursors. In this work, X-ray diffraction, AFM, ellipsometry, and UV–vis-spectroscopy are used to show that the crystallographic orientation, optical properties, band gap, and surface roughness of the derived films are correlated and can be varied by controlling deposition temperature and film thickness. The band gap of the samples varies between 2.70 and 2.35 eV. The observed growth rate varies between 0.1 to 1 Å/cycle depending on deposition temperature and the number of cycles. This large variation in growth rate provides an interesting case of ALD growth, which can be rationalized in terms of a geometric crystal growth model