Structural and Mechanical Properties of TaZrN Films: Experimental and ab initio Studies

This paper reports on the growth and characterization of the structural and mechanical properties of tantalum zirconium nitride films and the subsequent simulation of these properties using an ab initio calculation based on density functional theory (DFT) within the generalized gradient approximation. The films were deposited by reactive unbalanced magnetron sputtering and their physical and chemical properties were studied by means of x-ray diffraction (XRD), Rutherford backscattering (RBS), and nanoindentation. XRD revealed that these films formed a solid solution and that the lattice constant decreased linearly with Ta content. RBS provided the elemental composition of the films. Nanoindentation was used to evaluate the hardness and the elastic modulus. The hardness was found to have high values for a Ta/(Ta+Zr) of 30% and 100%. The elastic modulus was found to increase monotonically with Ta content. The intrinsic elastic constants were calculated using DFT and the results were compared to the experimental values. A correlation between the computational and the experimental Young’s modulus was established. However, the trends observed for the measured hardness and the calculated shear modulus were not in agreement. This disagreement was due to the prominent extrinsic component of the hardness for these materials. © 2006 American Institute of Physics

Grain Boundary Sliding Mechanisms in ZrN-Ag, ZrN-Au, and ZrN-Pd Nanocomposite Films

Nanocomposite films of ZrN-Me (Me = Ag, Au, or Pd) were produced by reactive unbalanced magnetron sputtering and were found to form a dense and homogeneous microstructure whereby nanocrystals of Me are distributed evenly throughout the ZrN matrix. Interestingly, the Young’s modulus was found to decrease much more dramatically with the increase in metal content for the ZrN-Ag system. A systematic ab initio study was undertaken to understand the mechanism of grain boundary sliding in these nanostructures. The maximum energy variation during the sliding was found to be the largest and the smallest for ZrN-Pd and ZrN-Ag, respectively

Correlation Between Interfacial Electronic Structure and Mechanical Properties of ZrN–Me (Me=Ag, Au, or Pd) Nanocomposite Films

Nanocomposite films of ZrN–Me (Me=Ag, Au, or Pd) were prepared using reactive unbalanced magnetron sputtering. The hardness and elastic modulus were measured by nanoindention and were found to vary differently with composition for the three nanocomposite structures. Young’s modulus was found to decrease much more dramatically with the increase in Me content for the ZrN–Ag system. These findings were attributed to the weaker bonding mechanism at the interface between the ceramic and the metallic phases, which is more prone to grain-boundary sliding as shown using first-principles calculations of the electronic structure at the interface for the three systems

Real-time Spectroscopic Ellipsometry Study of Ultrathin Diffusion Barriers for Integrated Circuits

The objective of this work is to monitor the growth process and the thermal stability of ultrathin tantalum nitride barrier nanostructures against copper diffusion in integrated circuits using real-time spectroscopic ellipsometry (RTSE). Single layers of copper and bilayer films of copper and tantalum nitride were produced on Si(111) substrates using unbalanced magnetron sputtering. The RTSE data was simulated using the Bruggeman effective medium approximation and a combined Drude-Lorentz model to obtain information about the growth process, film architecture, interface quality, and the conduction electron transport properties for these structures. The results deduced from the RTSE were verified by characterizing the structural and the chemical properties of the fabricated films using x-ray diffraction, Auger electron spectroscopy, and Rutherford backscattering. The effectiveness of the tantalum nitride barrier to stop the diffusion of copper into silicon was evaluated, monitoring their optical properties when annealed at 720 degreesC. The dielectric function of the films changed from a metallic to an insulating character when the diffusion proceeded. Also, the RTSE provided valuable information about the microstructure and the kinetics of the phase transformations that occur during heat treatment. (C) 2004 American Institute of Physics

Association of anthropometric qualities with vertical jump performance in elite male volleyball players

Aim: The objective of this study was to examine the association between physical and anthropometric profiles and vertical jump performance in elite volleyball players. Methods: Thirty-three elite male volleyball players (21±1 y, 76.9±5.2 kg, 186.5±5 cm) were studied. Several anthropometric measurements (body mass, stature, body mass index, lower limb length and sitting height) together with jumping height anaerobic power of counter movement jump with arm swing (CMJ arm)) were obtained from all subjects. Forward stepwise multiple linear regression analysis was performed to determine if any of the anthropometric parameters were predictive of CMJ arm. Results: Anaerobic power was significantly higher (P≤0.05) in the tallest players relative to their shorter counterparts. A significant relationship was observed between CMJ arm and lower limb length (r 2=0.69; P<0.001) and between the lower limb length and anaerobic power obtained with CM-J arm(r 2=0.57; P<0.01). While significantly correlated (P≤0.05) with CMJ arm performance, stature, lower limb length/stature and sitting height/stature ratios were not significant (P>0.05) predictors of CMJ arm performance. Conclusion. This study demonstrates that lower limb length is correlated with CMJ arm in elite male volleyball players. The players with longer lower limbs have the better vertical jump performances and their anaerobic power is higher. These results could be of importance for trained athletes in sports relying on jumping performance, such as basketball, handball or volleyball. Thus, the measurement of anthropometric characteristics, such as stature and lower limb length may assist coaches in the early phases of talent identification in volleyball

Optical and photoelectronic properties of a new material:Optoelectronic application

With the aim of studying the optical, electrochemical, and electronic properties of a new porphyrin-based material, we have synthesized a new porphyrinic complex, namely the (4,4$^{\prime}$-bipyridine)(meso-tetratrifluoromethylphenylporphyrinato)zinc(II) 4,4$^{\prime}$-bipyridine disolvate dihydrate complex with the formula [Zn(TFMPP)(4,4$^{\prime}$-bipy)]${\cdot }$2(4,4$^{\prime}$-bipy)${\cdot }$2H2O (I). This species is characterized by single-crystal X-ray molecular structure. The optical study is performed by UV–visible absorption and fluorescence spectroscopy. The fluorescence intensity presents an emission in the UV–visible range, indicating that this compound can be used as an optoelectronic material. The optical energy gap is 1.95 eV, and the current–voltage characteristics and impedance spectroscopy measurements have been studied to define the electronic properties of the zinc (II) porphyrin complex. The barrier height ${\phi }_{\mathrm{b}}$ is calculated, and the space-charge limited current mechanism is found to control the conductance. The results from the electronic study confirm that our porphyrin derivative can be used for various optoelectronic applications