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A method to study temperature dependent thickness variation of thin films has been developed based on angle and energy dispersive x-ray reflectivity (EDR) techniques. The data analysis scheme developed for this method combines both energy and angle dispersive x-ray reflectivity (ADR) profiles. The ADR technique provides the electron density profile on an absolute scale and the EDR technique facilitates rapid collection of reflectivity data as a function of temperature. We demonstrate the utility of the developed method with results of a study of thermal expansion of single and bilayer polymer films. We could detect a change of the thickness of the film in angstroms and could demonstrate interplay of negative and positive thermal expansions of dissimilar polymer layers in determining density profiles of polymer–polymer interface as a function of temperature. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Using synchrotron x-ray diffraction and reflectivity, we studied the transition from the paramagnetic NiMn phase to the chemically ordered, antiferromagnetic L10 phase of NiMn/Fe19Ni81 thin films deposited on a Si/SiO2 substrate as a function of the annealing temperature. The transformation to a dominating L10-ordered NiMn film takes place between 300 and 400 °C irrespective of the irradiation. This is also consistent with magnetization reversal measurements of the corresponding permalloy layers. The benefit of the ion irradiation is a reduction of the mosaicity for both the NiMn and the permalloy film, and a smoothening of internal interfaces. [ABSTRACT FROM AUTHOR]

An all-electrical method is presented to determine the exchange constant of magnetic thin films using ferromagnetic resonance. For films of 20 nm thickness and below, the determination of the exchange constant A, a fundamental magnetic quantity, is anything but straightforward. Among others, the most common methods are based on the characterization of perpendicular standing spin-waves. These approaches are however challenging, due to (i) very high energies and (ii) rather small intensities in this thickness regime. In the presented approach, surface patterning is applied to a permalloy (Ni80Fe20) film and a Co2Fe0.4Mn0.6Si Heusler compound. Acting as a magnonic crystal, such structures enable the coupling of backward volume spin-waves to the uniform mode. Subsequent ferromagnetic resonance measurements give access to the spin-wave spectra free of unquantifiable parameters and, thus, to the exchange constant A with high accuracy. [ABSTRACT FROM AUTHOR]

We report on the formation of a regularly ordered void lattice with a void size of about 4 nm in an alumina matrix. The voids were formed by thermal treatment of a well-ordered three-dimensional Ge quantum dot lattice formed earlier by self-assembled growth in an alumina matrix during magnetron sputtering codeposition of Ge+Al2O3. During the subsequent annealing the germanium atoms were lost from the film and so voids were produced. The positions of the voids are ordered in the same way as the Ge quantum dots that were present before annealing, while their sizes can be controlled by the deposition parameters. [ABSTRACT FROM AUTHOR]

• Impurity concentrations of ALD grown HfO 2 films were determined using ERDA. • The GPC correlates with the H impurity level and the layer thickness uniformity. • GIXRD was used to determine the crystal structure, crystal size and crystallinity. • Spots arising in the HfO 2 topography coincide with the onset of crystallisation. Hafnium oxide was deposited from tetrakis(dimethylamino)hafnium (TDMAHf) and water by atomic layer deposition (ALD) on heated 4 ″ Si wafers covered with native oxide in the temperature range from 100 ° C to 350 ° C. Optimized self-limiting ALD reaction and smallest hydrogen impurity level have been realized for a substrate temperature of 300 ° C. The stoichiometry of deposited films and hydrogen impurity level were measured by elastic recoil detection analysis. The hafnium to oxygen ratio showed the expected 1:2 value. Besides hydrogen, no other impurities could be detected. Furthermore, a strong correlation between the growth rate per cycle (GPC), film uniformity and level of hydrogen impurities was observed. In addition, the characterization of the crystal structure showed the appearance of some crystallites in an amorphous matrix already for a growth temperature of 250 ° C and a pure crystalline layer at a growth temperature of 350 ° C. The increased crystallinity with increasing growth temperature was attributed to a higher seed concentration and a nearly constant crystal size. [ABSTRACT FROM AUTHOR]

Abstract Sputter deposited Mg 2 Fe x Si 1-x films of 250 nm thickness have been investigated by means of Mössbauer spectroscopy. While non-hydrogenated films are characterized by a quadrupole split doublet, hydrogenated regions show a singlet with reduced isomer shift. The relative areas of the spectra reflect the relation between loaded and unloaded regions prepared at the same loading conditions. [ABSTRACT FROM AUTHOR]

Abstract: The A1→L10 phase transition of Fe50Pt50 films, deposited at room-temperature on amorphous SiO2 by dc magnetron co-sputtering at 0.3Pa, was studied with in-situ X-ray diffraction. An almost complete transition characterized by a long-range order parameter S >0.8 is obtained already after a heat treatment at (320±20)°C. A post-deposition He ion irradiation (50keV, 1×1015 −3×1016 cm−2) does not further reduce the transition temperature. Theoretical calculations reveal that, due to the negligible thermalization of the sputtered atoms and reflected ions in the plasma, a considerable fraction of energetic ions and atoms meet the substrate surface. The low transition temperature is explained by the impact of energetic ions and atoms which provoke significant adatom mobility and a decrease of the activation energy for atomic reordering by vacancies. Consequently, using deposition parameters leading to a strong thermalized plasma, the FePt films showed an increase of the transition temperature up to 400°C, a lower S-value (S ≅0.6) and a reduced coercivity. [Copyright &y& Elsevier]