Real time spectroscopic ellipsometry study during the growth of nanocrystalline nitride protective coatings

摘要

Real time spectroscopic ellipsometry (RTSE) was employed to study the optical, electronic, and transport properties of various classes of nanocrystalline nitride coatings grown by reactive unbalanced magnetron-sputtering. The investigated materials include TaZrN and NbZrN solid solutions, and nc-ZrN/Ag and nc-ZrN/Ni nanocomposites. Film properties were tailored by varying film composition. The following models were used to interpret the ellipsometric data: (a) effective medium theories describing the heterostructures in terms of their constituent materials and (b) a combined Drude-Lorentz model describing the optical response of the conduction and valence electrons. A correlation was found between the optical data and the chemical composition using the linear and Bruggeman effective medium approximations for the solid solution and the nanocomposite materials, respectively. The Drude-Lorentz model provided extensive information regarding the optical and electronic properties of the films (plasma frequency, electron mean free path, electrical resistivity, and band structure). For example, a correlation was made between the conduction electron mean free path and the grain size in nanocomposite films. RTSE findings were confirmed using x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy. (C) 2004 American Vacuum Society.