MOCVD template approach to the fabrication of free-standing nickel(II) oxide nanotube arrays: Structural, morphological, and optical properties characterization

Ordered homogeneous arrays of nickel (II) oxide nanotubes have been fabricated through an MOCVD template route using Ni(tta)(2)tmeda (Htta = 2 thenoyl-trifluoroacetone, tmeda = tetramethylendiamine) as a source. The X-ray diffraction pattern shows the formation of the NiO cubic phase. Scanning electron microscopy (SEM) images of the NiO nanotubes, after removing the template, indicate the formation of well ordered nanotube arrays. There is evidence, through transmission electron microscopy studies, that nanotubes are opened on both sides. The optical properties of NiO nanotubes, determined using spectroscopic ellipsometry, strongly depend on the polarization direction of the light electric field, indicating optical anisotropy that relates to the vertical alignment of nanotubes.