Compensating effects of platinum in n- and p-type silicon

Spreading resistance measurements have been used to investigate compensating effects of ion-implanted and diffused platinum in both n- and p-type silicon. The conversion resistivity-platinum concentration has been obtained by solving the charge neutrality condition, which requires a knowledge of the entropy factors associated to the ionization of the two energy levels introduced by the platinum inside the silicon bandgap. We have measured entropy factor values of 25±2 and of 2±0.3 for the donor and the acceptor level, respectively, and by using these values the silicon resistivity versus platinum concentration has been calculated for different values of the substrate dopant concentration. As the platinum acceptor level is shallower than the corresponding level introduced by gold doping, a large difference in the resistivity increase induced by the two elements in n-type silicon is expected. We will show that this large difference is however smoothed by the different values of the corresponding entropy factors.     

Anisotropy in the magnetic susceptibility of 2H-TaSe2

The magnetic susceptibility of 2H-TaSe₂ is temperature dependent and anisotropic. The susceptibility with H parallel to the c axis is approximately 2.5 times that perpendicular. The decrease in susceptibility below the charge density wave transition at 122 K is also anisotropic with [χ₆(122 K) ? χ₆(4.2 K]?[χ_⊥(122 K) ? χ_⊥(4.2 K)] ≈ 4. Consequently, this change cannot be simply interpreted as a change in the density of states at the Fermi level, unless very anisotropic electron g values are assumed.     

Study of stress induced leakage current by using high resolution measurements

A thorough characterization of stress-induced leakage currents (SILCs) for a IOnm-thick oxide, by using the floating-gate technique, is presented. The obtained current is modeled by a volume-limited conduction mechanism. Experimental and model suggest that SILC conduction mechanism is the same in thin as well as in thick oxides.     

A substructure approach tailored to the dynamic analysis of multi-span continuous beams under moving loads

The paper deals with the dynamic analysis of multiply supported continuous beams subjected to moving loads, which in turn can be modelled either as moving forces or moving masses. A dedicated variant of the component mode synthesis (CMS) method is proposed in which the classical primary-secondary substructure approach (SA) is tailored to cope with slender (i.e. Euler-Bernoulli) continuous beams with arbitrary geometry. To do this, the whole structure is ideally decomposed in primary and secondary spans with convenient restraints, whose exact eigenfunctions are used as assumed local modes; the representation of the internal forces is improved with the help of two additional assumed modes for each primary span, while primary-secondary influence functions allow satisfying the kinematical compatibility between adjacent spans; the continuous beam is then re-assembled, and the Lagrange's equations of motion are derived in a compact block-matrix setting for both moving force and moving mass model. Numerical examples demonstrate accuracy and efficiency of the proposed procedure. An application with a platoon of high-speed moving masses confirms that the inertial effects neglected in the moving force model may have a significant impact in the structural response.     

Measurement of the total photoabsorption cross section on a proton in the energy range 600–1500 MeV at the GRAAL

The total photoabsorption cross section on a free proton was measured at the GRAAL facility in the energy range E _γ = 600−1500 MeV. The large-aperture LAGRANγE detector and a liquid hydrogen target were used in the experiment performed with a back-scattered Compton gamma beam. To improve the accuracy, two alternative methods were employed. First, a subtraction method of using empty-target measurements allowed the cross section σ _tot to be evaluated directly because of a low level of the electromagnetic background. Second, an algorithm for evaluating σ _tot on the basis of summing the dominating partial cross sections was developed. Experimental results obtained for σ _tot by the two methods are compared with existing data. The article was translated by the authors. Published in Russian in Yadernaya Fizika, 2008, Vol. 71, No. 1, pp. 76–83.     

Double pi(0) Photoproduction on the Proton at GRAAL

The double pi(0) photoproduction off the proton has been measured in the beam energy range of 0.65-1.5 GeV. The total and differential cross sections and the Sigma beam asymmetry were extracted. The total cross section measured for the first time in the third resonance region of the nucleon shows a prominent peak. The interpretation of these results by two independent theoretical models infers mostly the selective excitation of P11- and D13-nucleon resonances.