Structural, optical and electrical properties of nanocrystalline TiO2 -- HfO2 thin films
In the present work the properties of mixed HfxTi1-xO2 solid solution thin films in metal-oxide-semiconductor (MOS) configuration have been studied. Thin films, were grown on monocrystalline silicon substrates using the low pressure hot target reactive sputtering from the Ti:Hf mosaic target. From optical transmission measurements the 3.42 (eV) bandgap of the thin films has been estimated. Electrical characterization of the prepared MOS structures shows classical capacitance- and current-voltage behaviors indicating medium-k gate oxide properties with the low leakage current
Characterization of nanocrystalline TiO2–HfO2 thin films prepared by low pressure hot target reactive magnetron sputtering
Abstract Thin films of oxides were deposited by magnetron sputtering in reactive oxygen plasma from Ti–Hf mosaic target. The low pressure of reactive gas and appropriate power of plasma discharge during the deposition assumed pseudoepitaxial conditions of the layer growth. Thin films were characterized by means of X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and optical transmission. On the basis of obtained results it was stated that the fabricated thin films were composed of the stoichiometric HfTiO 4 single phase with average size of grains in the range of tenth of nanometers. Optical absorption spectra, derived in a conventional way from optical transmission measurements, yielded the optical band gap of about 3.42 eV. The grain size has changed after annealing in the range of 30 to 40 nm.
Examination of the sputtering profile of NiTi under target heating conditions
In this paper we have examined compositional shifts in NiTi film sputter-deposited from a heated and a cooled target. Substrates were radially placed at 18° intervals to capture the semicircular sputtering profile. The composition of the film was measured using Rutherford backscattering spectroscopy (RBS). Film thickness values were measured and the atomic flux captured was calculated. Results indicate that the target temperature significantly influences the composition of the sputtered film. It was found that, for cold targets, Ni and Ti sputter at different angles, producing a compositional shift in the film when compared with the target. For hot targets the sputtering angle is influenced to a lesser degree, such that the compositional shift is negligible. Therefore, target temperature appears to represent an approach to alter the stoichiometry of films deposited.