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.
The REX-ISOLDE project
The Radioactive Beam Experiment REX-ISOLDE [1–3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE.