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The authors have determined the critical composition xc of the percolation threshold in polycrystalline AlxSi1-x thin films with a new method, using structural arguments only. The result xc=(0.55+or-0.05) agrees with the results of the commonly used methods. Moreover, the model explains the wide spread of experimental values of xc as reported in the literature.

In the present paper the dependences of the resistivity p and the Hall voltage UH of polycrystalline Ni-Cu and Ta-Cu multi-layered thin films on the layer thickness dr are discussed. The thickness dependence of p and UH can be well understood using a simple model in which the layers are considered as parallel resistors, whereby the resistivity of a single layer is enhanced via surface scattering described by the well known Fuchs-Namba size theory. The Hall coefficients are independent of the layer thickness, although the measured Hall voltage varies with dr owing to the enhancement of the individual layer resistivities. For very thin layers, i.e. if the layer thickness becomes smaller than the layer roughness, the experimental data on both p and UH indicate a breakdown of the multi-layered structure to an island-like clustered film structure. For Ni-Cu a crossover from ferroparamagnetic to superparamagnetic behaviour was observed at this critical thickness.

Grain boundaries are known to reduce significantly the electrical dc conductivity of polycrystalline metallic materials. In this paper, we give a quantum mechanical calculation of the grain-boundary resistance based on the transfer-matrix approach. The results show an exponential decrease of the conductivity with respect to the number of grain boundaries per mean free path in accord with an empirical model proposed recently.

Direct observation of surface roughness on metal films is a longstanding problem in thin film characterization. In this work the high quality of scanning tunnelling microscopy (STM) was used for investigation of evaporated gold films. A scanning tunnelling microscope able to scan areas up to 0.8 × 0.8 micro m with high reproducibility is presented. The topography of 80 nm thick gold films grown under identical evaporation conditions was investigated as a function of the selected substrate material (Corning glass, silicon, NaCl, mica and highly oriented pyrolitic graphite (HOPG)). The incipient growth mechanism on the substrate is the primary reason for the surface roughness. The real space images of the surface topography correlate very well with knowledge achieved from former growth experiments given in the literature. Moreover, very flat gold surfaces on HOPG allowed the observation of atomic corrugations in air environments.

The work function of metallic thin films limited by symmetric surfaces is expected to be thickness dependent at a level of 0.1 eV and a thickness range of about 5 nm. Recent experiments, however, demonstrated that Cu films on glass or Ni substrates show a long ranging (10–20 nm) increase of the work function with increasing film thickness [1]. This effect was attributed to a violation of local charge neutrality in films with unlike surfaces. In this paper we show that the barrier height of thin film diodes like metal-insulator-metal (MIM)-, metal-semiconductor (Schottky contacts)-and metal-vacuum-metal (Kelvin capacitors) structures decreases with increasing thickness of one metal electrode. This metal electrode consists of a double layer whose single layer thicknesses are of the order of few tens of nm. The observed effect can be attributed to a decrease of the work function at the counter limiting interface not exposed to the evaporation beam. A possible explanation can be found again in the violation of the local charge neutrality in films with unlike surfaces.

A novel chemical approach was demonstrated for the growth of high-quality, silver films by CVD. This concept relies on the catalytic reactivity of cationic silver, and of silver surfaces with alcohols. This leads to high-purity films using either state-of-the-art precursors or silver salts that have not been yet considered as CVD precursors. The occurrence of the catalytic oxidative-dehvdrogenation of alcohols, considered as the driving force in this process, was shown by in-situ mass spectrometry (MS). Films of fcc-Ag with p

Magnetostrictive tunnel magnetoresistance (TMR) sensors pose a bright perspective in micro- and nano-scale strain sensing technology. The behavior of TMR sensors under mechanical stress as well as their sensitivity to the applied stress depends on the magnetization configuration of magnetic tunnel junctions (MTJ)s with respect to the stress axis. Here, we propose a configuration resulting in an inverse effect on the tunnel resistance by tensile and compressive stresses. Numerical simulations, based on a modified Stoner–Wohlfarth (SW) model, are performed in order to understand the magnetization reversal of the sense layer and to find out the optimum bias magnetic field required for high strain sensitivity. At a bias field of −3.2 kA/m under a 0.2 × 10 - 3 strain, gauge factors of 2294 and −311 are calculated under tensile and compressive stresses, respectively. Modeling results are investigated experimentally on a round junction with a diameter of 30 ± 0.2 μ m using a four-point bending apparatus. The measured field and strain loops exhibit nearly the same trends as the calculated ones. Also, the gauge factors are in the same range. The junction exhibits gauge factors of 2150 ± 30 and −260 for tensile and compressive stresses, respectively, under a −3.2 kA/m bias magnetic field. The agreement of the experimental and modeling results approves the proposed configuration for high sensitivity and ability to detect both tensile and compressive stresses by a single TMR sensor.