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Investigates the effects of deposition parameters on film structural and magnetic properties and the preparation of iron nitrogen films. Use of Auger electron spectroscopy and x-ray diffraction; Overview of the magnetic properties of the films; Saturation of the magnetization of the iron films.

The nonequilibrium epitaxial growth process of MgxCa1-xO solid-solution films at 600°C is carefully investigated. No obvious phase separation is observed until annealing at 800°C despite a large miscibility gap. The solid-solution film is featured with disorder alloy as confirmed by transmission electron microscopy (TEM). Spinodal decomposition caused by uprising diffusion happens after short-time annealing which explicitly indicates the structure stability of the metastable solid-solution films does result from diffusion quenching. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the growth of fractal patterns during ion beam-solid interaction in a nickel-zirconium alloy thin films. Analysis of the isotropic and anisotropic characteristics of the thin films; Determination of the fractal dimension of isotropic fractal patterns; Discussion on the possible growth mechanism of the fractal patterns.

Epitaxial growth and magnetic properties of Co thin films on GaN(0001)-1×1 surfaces are studied. The films show degraded saturation magnetization due to the interfacial interaction. On excess-Ga-induced pseudo- 1×1 surface, 30°-rotation domains in the Co epilayer are inevitable and the films show in-plane magnetic anisotropy. By annealing the starting surface of pseudo-1×1 and to achieve a Ga-less 1×1 surface, single domain Co epifilms having orientations aligned with the substrate can be grown, which facilitates in-plane uniaxial magnetic anisotropy. [ABSTRACT FROM AUTHOR]

We have demonstrated visible and ultraviolet random laser actions simultaneously from highly disordered ZnO polycrystalline thin films under optical excitation. It is found that the realization of ZnO grain boundaries by thermal annealing can provide sufficient optical gain (i.e., related to deep-defect-level radiative recombination) and coherent feedback to achieve random laser action at visible wavelength. Furthermore, the coexistence of visible and ultraviolet random lasings inside the highly disordered ZnO films is due to the size difference of the random cavities at different wavelengths. [ABSTRACT FROM AUTHOR]

Random lasing was observed from ZnO polycrystalline thin film deposited by filtered cathodic vacuum arc technique. It is found that the random lasing action results from exciton-exciton scattering process when the excitation intensity is low. However, with increasing excitation intensity, the well-resolved discrete lasing modes evolve into broad stimulated emission band due to electron-hole plasma formation when the photogenerated exciton density exceeds the Mott density. The short spontaneous emission decay time measured at low temperature suggests that the radiative recombination rate is enhanced by the nanosized ZnO grains in the polycrystalline film through exciton-light coupling. [ABSTRACT FROM AUTHOR]

An ion-beam technique has been employed to fabricate nanoscale needlelike structures in ZnO thin films on silicon and plastic substrates at room temperature. The ZnO nanoneedles showed a single-crystalline wurtzite structure, the stem of which was around 100 nm in diameter. The sharp tips of the nanoneedles exhibited an apex angle of 20° as measured by transmission electron microscopy. Room-temperature ultraviolet random lasing action was observed in the ZnO nanoneedle arrays under 355 nm optical excitation. [ABSTRACT FROM AUTHOR]

The lasing characteristics of highly disordered ZnO thin films deposited on SiO2/Si substrates with and without a MgO buffer layer have been investigated. We observed that the emission spectra of the ZnO epilayers with and without a MgO buffer are associated with the radiative recombination of free-exciton (∼380 nm) and electron-hole plasma (∼395 nm), respectively. The difference in the lasing wavelength is due to the induced compressive (tensile) strain along the c axis of the ZnO epilayers as a result of the presence (absence) of the MgO buffer layer. It is demonstrated that the strain-induced variation of Mott density inside the ZnO epilayers is responsible for the observed lasing characteristics. [ABSTRACT FROM AUTHOR]

A composite hardness model based on the function of depth weight factor is presented. The model can be applied to determine the characteristic hardness of surface coatings which are too thin for the hardness to be directly measured. Its application requires only composite hardness data obtained from coated specimens by conventional microhardness measurement. DLC, TiN, and Cu films on substrates of glass, silicon, and AISI 52100 steel were used to verify this composite hardness model. It proved valid for a variety of cases. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]