Thermal annealing effects on grain boundary recombination activity in silicon

We have studied the influence of conventional and rapid thermal treatments at 850°C for 30 min and 10 s, respectively, on the recombination activity of the9,13 (P-type) and25 (N-type) grain boundaries in silicon. The analyses were made by scanning electron microscopy (SEM) working in the electron beam induced current mode (EBIC) and completed by minority carrier diffusion length measurements. The main result obtained from this study shows the importance of the rapid thermal process as a suitable thermal treatment for polycrystalline materials.     

Investigation of the Cu-Zr-Y oxides activity in the carbon black catalytic oxidation by differential thermal analysis and temperature programmed reduction

Different copper/zirconium-yttrium catalysts have been tested in carbon black oxidation reaction. Supported mainly on differential thermal analysis and temperature programmed reduction, two different mechanisms have been proposed to explain the catalytic results. In the absence of copper, it has been shown that Zr³⁺ ions and associated anionic vacancies are responsible to the catalytic enhancement observed in the mixed oxides, oxygen species being activated on these sites. Among mixed zirconia-yttria solids, ZrO₂-5 mol%Y₂O₃ is the most active catalyst. Copper impregnation on these oxides leads to the formation of different copper species. Small particles of CuO in low interaction with the support, induce a catalytic improvement due to the highest reducibility of these species. Moreover, in order to be more efficient, CuO species should have some interactions with the support, since impregnated samples are more active than the simple mechanical mixtures.     

Solubility limit of impurities in silicon after laser induced melting

The solubility of several dopants (Sb, Ga, Bi, In) in laser treated silicon has been investigated. The dopants were introduced by vacuum deposition followed by ruby laser irradiation. Their solubility was determined by Rutherford backscattering spectroscopy measurements in channelling and random conditions. In all cases, a maximum solubilityC _S ^* , much higher than the equilibrium solubility limitC _S ⁰ and independent of the pulsed laser energy density, was found. The values obtained are in good agreement with those calculated from a simple model based on phase diagram considerations, using the relationship: $$C_S^* = \frac{{C_S^0 }}{{k_0 }}k^* ,$$ wherek ₀ andk ^* are the equilibrium and effective distribution coefficients. Finally, the existence of a new solubility limit for a laser treatment is discussed.     

TSC defect level in silicon produced by irradiation with muons of GeV-energy

Deep level transient spectroscopy has been used to observe the reduced concentrations of vacancy-related defects in γ-irradiated n-type Si containing hydrogen atoms. Data are presented on the efficiency and depth of this damage reduction as a function of the duration and temperature of the exposure to the plasma used to introduce the atomic hydrogen. A 3-hour exposure in an H plasma at 300°C prior to irradiation reduced the concentrations of the O-V, V-V and P-V centres by half or more to a depth of ～20 μm, compared to the control samples.     

An infinite family of homogeneous polynomial self-maps of spheres

We provide an infinite family of homogeneous polynomial self-maps of spheres. Furthermore, we identify the gradient map of the Cartan–Münzner polynomial as a member of this infinite family and thus supply it with a geometric meaning.     

The decay of 187Pt: Comparison of the levels of 187Ir with those of heavier odd mass iridium isotopes

The decay scheme of 2.35 h ¹⁸⁷Pt has been investigated using isotopically separated samples produced by the ISOLDE facility at CERN. A total of 20 excited levels in ¹⁸⁷Ir have been established. For many of these levels, spin, parity and absolute probabilities of depopulating transitions have been determined. The results indicate that the ¹⁸⁷Ir nucleus can be described in terms of a single particle Nilsson model including Coriolis coupling between bands ($\text{3}\text{2}{}^{\mathrm{+}}\text{[402],}\text{1}\text{2}{}^{\mathrm{+}}\text{[400]}$).     

Analysis of UV-Laser induced oxidation of implanted silicon by optical reflectivity measurements

The oxidation of ion implanted silicon induced by a repetitive excimer laser working in liquid phase regime has been monitored by a simple in situ technique. It consists to follow the optical reflectivity at the wavelength 633 nm of the silicon samples under irradiation. The influence of implantation and laser irradiation conditions on the oxidation process has been investigated by this technique. The results obtained have been compared using infrared absorption data. The role of the Si/SiO₂ interface roughness on the oxide film quality has been studied.     

Carbon analysis in CdTe by nuclear activation

We describe the capabilities of the nuclear reaction the measurement of absolute concentrations of C in CdTe by the charged particle activation (CPA) method. This technique is used to determine the segregation coefficient of C introduced as an impurity in CdTe.     

Total Oxidation of Propene and Toluene on Copper/Yttrium Doped Zirconia

The catalytic oxidation of propene and toluene has been investigated on pure ZrO₂, pure Y₂O₃, and ZrO₂ doped with 1, 5, and 10 mol % Y₂O₃ in the presence or absence of copper (0.5, 1, and 5 wt%). A synergetic effect has been detected since ZrO₂ and Y₂O₃ exhibit significantly lower activities than the mixed oxides. The higher surface areas, related to structural change from mononoclinic (ZrO₂) to tetragonal (ZrO₂–;;Y₂O₃), partly explained the higher activity of ZrO₂–;;Y₂O₃. However, it has been shown that the number of anionic vacancies, created by the substitution of Zr⁴⁺ by Y³⁺, in yttria-stabilized zirconia solids depends on the yttrium contents. Their effect on propene and toluene oxidation activity is significant. The anionic vacancies should induce better activity of the ZrO₂—5 mol % Y₂O₃ catalyst with or without copper, which presents the higher number of Zr³⁺ species. This support should favor the formation of CuO particles, which should be the most active catalytic sites in the studied reaction.