Thin films of cadmium selenide (CdSe) were grown by the chemical bath deposition (CBD) technique. The effects of the common grain growth promoter, cadmium chloride (CdCl2) and annealing on the films were investigated. X-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM), atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDS) measurement techniques are used to determine the crystalline structure, surface morphology and composition of the as-deposited and annealed films. Noticeable changes in XRD patterns were observed on the annealed films. The as-deposited films of poor crystalline quality are transformed into crystalline hexagonal phase of CdSe. The annealing and CdCl2 treatment affects the grain growth, which is stronger for the CdCl2 treated samples. The optical properties of the films were investigated by optical transmittance and photoluminescence (PL) spectroscopy. The optical band gaps of the films are estimated using the optical transmittance measurements. A decrease in the band gap is observed for the annealed films with or without CdCl2 addition. Photoluminescence peak intensity due to the near band edge luminescence is found to increase with annealing and it increases pronouncedly by annealing with CdCl2 treatment. This effect can be attributed to the enhancement of the crystallinity of the films. Nevertheless, films annealing after CdCl2 treatment resulted in selenium vacancies, which display a band emission centred at 1.4 eV.

The properties of Sb-based III-V semiconductor compounds for optoelectronic applications in the mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) range were reviewed. The growths of the Sb-based binary, ternary and quaternary were studied by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). The structural, optical and electrical characterizations were carried out. Focal plane array, photoconductors and photodiodes were fabricated for the MWIR and LWIR range. Doublehetero structure (DH), multi-quantum well (MQW) and strained superlattice (SSL) lasers in the 3–5 μm range were fabricated. InAs-GaSb type-II superlattices were designed, grown and fabricated into photodetectors for the MWIR and LWIR range.

Materials such as glasses, insulated foams, polymers are semi-transparent. In order to measure the phononic diffusivity of such media – in which the heat transfer is both conductive and radiative – it is necessary to develop a complete methodology. The technique, we propose here, is an extension of the Flash method with the use of a semi-analytical combined model. It permits to determine the diffusivity of materials such as glass and silica for a large range of temperature (from 300 K to 700 K).

Hydrogen related defects in high purity n-type float zone silicon samples have been studied by means of Deep Level Transient Spectroscopy. They were introduced, as well as the characteristic vacancy-oxygen (VO) and divacancy (${\rm V}_2$) centers, by MeV proton implantation. Two hydrogen related defect levels were resolved at 0.32 eV and 0.45 eV below the conduction band edge (Ec). Careful annealing studies indicate strongly that a third hydrogen related level, overlapping with the singly negative charge state level of ${\rm V}_2$, is also present in the implanted samples. The annealing behavior of the hydrogen related defects has been compared with literature data leading to a rather firm identification. The $E_{\rm c}-0.32$ eV level originates from a VO center partly saturated with hydrogen (a VOH complex) while the $E_{\rm c}-0.45$ eV level may be ascribed to a complex involving a monovacancy and a hydrogen atom (a VH complex). The third hydrogen related defect is tentatively ascribed to a complex involving a hydrogen atom and a divacancy (a ${\rm V}_2{\rm H}$ complex).

Benefits from laser Peening have been demonstrated several times in fields like fatigue, wear or stress corrosion cracking. However, in spite of recent work on the calculation of residual stresses, very few authors have considered a finite element method (FEM) approach to predict laser-induced mechanical effect. This comes mainly from the high strain rates involved during LP (106 s−1), that necessitate the precise determination of dynamic properties, and also from the possible combination of thermal and mechanical loadings in the case of LP without protective coatings. In this paper, we aim at presenting a global approach of the problem, starting from the determination of loading conditions and dynamic yield strengths, to finish with FEM calculation of residual stress fields induced on a 12% Cr martensitic stainless steel and a 7075 aluminium alloy.

The aim of this work is to study and design a NMR micro antenna dedicated to ultrasound lesion monitoring by imaging. This micro-antenna will be associated with an oesophageal ultrasound applicator used for oesophagus tumour therapy to provide guidance and monitoring by magnetic resonance imaging (MRI). So, the micro-antenna design was guided by size and shape constraints due to endocavitary applications and adaptation to the ultrasound applicator. In this scope, a coil of N rectangular loops was built. In order to minimise size and offer the ability to perform in vivo adjustments, remote tuning and matching was performed. MRI investigations were carried out using two antennas: a volumic transmitter coil for excitation and this endoscopic receiver coil for signal capture. Lesion can be clearly seen on T2-weighted MR imaging. Lesion measurements on sagittal and axial slices gave a good correlation with lesion dimensions measured on sample.

Results of the comprehensive study of deuterium-implanted hexagonal SiC (4H and 6H) using optical absorption and infrared measurements, elastic recoil detection analysis, thermal desorption and positron annihilation spectroscopies are reported. It is shown that implanted deuterium mainly forms bonds with lattice atoms. The amount of deuterium in the form of interstitial molecules and in vacancies is considerably smaller. Ion implantations with fluences exceeding 1015 D+/cm−2 create point defects in concentrations sufficiently high for complete positron trapping. Recrystallisation of the amorphised SiC does not remove the positron traps.

Barium metaplumbate thin films were deposited in situ by pulsed laser deposition on Si/SiO2/Ti/Pt substrates with a high deposition rate. The temperatures used ranged between 400 °C and 700 °C. As the deposition temperature was increased, the films assumed a strong (222) preferential orientation. This orientation of the electrodes was reflected on the PZT films, having a very big influence on their ferroelectric behavior. The PZT films made over BPO deposited at high temperature presented high values of remanent polarization (43 μC/cm2) but indications of high leakage currents could be observed in the hysteresis loops. By using BPO bottom electrodes, a 30% improvement in the fatigue behavior of PZT capacitors when compared with the normal platinum electrodes was observed.

The matching method is used to analyse the scattering of elastic waves by a structural defect made up several atomic chains surmounting an infinite lattice plane. The vibrational dynamics of the structure is considered within the harmonic approximation framework. The propagating continuum associated to the two vibrational eigenmodes of the perfect lattice is determined and discussed. The localised states induced by the defect are calculated and analysed for heavy and light adatom masses. Their interest appears during the investigation of the diffusion spectra. These localised states allow the interpretation of some observed structures in terms of Fano resonances. It is shown that the resonance number decrease in transmission spectra of light adatom case. The Fano resonances can be absent in the transverse mode, but are always present in the longitudinal one. Their position shifts slightly towards the high frequencies when the number N of perturbating chains increases. When N is higher than the unity, oscillations of Fabry-Perot type appear in the transmission spectra. The number of these oscillations is directly related to the number of adatomic linear chains, in the light and heavy mass cases, in both eigenmodes. We also observe the existence of zeros transmission in the spectra. Because of the large size of the dynamical matrices and complicated graphical resolution spectra, we have limited our study to eight perturbating adatomic linear chains.

A photothermal microscope devoted to microscopic thermal and thermo-elastic characterizations is presented. In thermal configuration, the sample is heated by an intensity modulated laser beam and the periodic temperature increase at the sample surface is detected using the photoreflectance technique. In thermo-elastic configuration, the periodic elevation of the sample surface is measured using a Nomarski interferometer. The spatial resolution is micrometric, the sensivity is better than 10−3 K/ $\surd$ Hz in thermal configuration and 10 pm/ $\surd$ Hz in the interferometric one. Typical photoreflectance thermal properties measurements are performed to evaluate the performance of the instrument. In thermo-elastic configuration, the interferometric signal has to be carefully analyzed to remove spurious photothermal effects. The thermo-elastic response of isotropic and anisotropic homogeneous samples during modulated photothermal experiments are then calculated to demonstrate that interferometric measurements enable quantitative determination of some of the sample thermo-elastic parameters such as thermal diffusivity, elastic anisotropy and crystalline orientation.

The number of scattering centres measured using channeled particles passing through a cavity layer formed by He implantation in silicon is shown to depend on the probe energy. This unusual result is explained in terms of interaction of channeled particles with atoms of cavity walls and dislocation lines. The Rutherford backscattering analysis in channeling incidence (RBS-C) is then used to study the time evolution of cavity and dislocation populations during annealing. It is shown that cavities are actually bubbles in equilibrium with the silicon matrix. The time to reach this equilibrium is related to the gas desorption. For our experimental conditions (40 keV, 5 × 1016 cm−2 and 800 °C), this equilibration time is about 10 minutes. Strain and dislocation build-up occur under shorter time scales, during which bubbles are probably overpressurized. The pinning of bubbles at dislocations must be taken into account to explain the evolution of these extended defects over a longer period.

In this paper a new method of stator-core lamination characterization, aimed at studying magnetic field in the vicinity of a machine, is proposed. This characterization, made with small signals over a wide frequency range, is useful to study high frequency magnetic behavior of motors fed by PWM static converters. Small minor hysteresis loops of magnetic steel are assimilated to ellipses and, neglecting anisotropy, any point of a stator-core lamination is characterized by two local parameters: the relative permeability and the resistivity. The proposed method consists in measuring the impedance of a test coil over a wide frequency range by an impedance analyzer and in comparing experimental results to theoretical predictions based on magnetic field diffusion equation. An algorithm yields values of local relative permeability and resistivity from inductance measurements and experimental values of resistances are used to control the result quality.

Standard [001]-oriented p- (12–20 Ω cm) and n-type (1.8–2.6 Ω cm) Czochralski (Cz) silicon wafers were treated by a RF (13.56 MHz) hydrogen plasma at a substrate temperature of 250 °C. After the plasma hydrogenation subsequent annealing was applied up to 600 °C in air. The formation of H2 molecules in voids/platelets was investigated by Raman spectroscopy. The Raman intensities of the H2 vibration modes at ~4150 cm−1 exhibited significant intensity modulations in dependence on the annealing temperature. The intensities of the H2 Raman lines indirectly monitor the evolution of the voids/platelets upon annealing. This assumption was verified by cross-sectional transmission electron microscopy (XTEM), which was applied for comparison. The intensity modulations of the H2 Raman signal can be explained by the evolution of $\{111\}$ and $\{001\}$ platelets. At lower annealing temperatures (<500 °C) platelets laying in $\{111\}$ planes are dominant, while at elevated temperatures (≥500 °C) [001]-oriented platelets become more and more important. $\{110\}$ platelets were also observed using XTEM measurements in p-type material. In case of p-type substrates the Raman intensities were significant higher than for n-type material. The higher H2 Raman intensities in p-type Cz Si can be explained by the amphoteric character of hydrogen in silicon.

This paper presents a non destructive evaluation systemfor rail inspection with a device embedded in a subway train. Thedifficult operating conditions lead to the design of a specificdouble-coils and double-frequencies sensor that delivers 8complementary signals. After the presentation of the technologicalsolution, the paper deals with the detection of minor defects andpresents three approaches: the first one is a time heuristicapproach, the second one is based on wavelet basis projections,and the last one implements an inverse filtering which allows thetransformation of the differential probe outputs into estimatedabsolute ones. The methods are validated statistically on alabeled defect data set with the help of ROC curves.

In this work we show that the cooling rate following a platinum diffusion strongly influences the electrical conductivity in weakly phosphorus doped silicon. Diffusions were performed at the temperature of 910 °C in the range of 8–32 hours in 0.6, 30, and 60 Ω cm phosphorus doped silicon samples. Spreading resistance profile analyses clearly show an n-type to p-type conversion under the surface when samples are cooled slowly. On the other hand, a compensation of the phosphorus donors can only be observed when samples are quenched. One Pt related acceptor deep level at 0.43 eV from the valence band is assumed to be at the origin of the type conversion mechanism. Its concentration increases by lowering the applied cooling rate. A complex formation with fast species such as interstitial Pt atoms or intrinsic point defects is expected. In 0.6 Ω cm phosphorus doped silicon, no acceptor deep level in the lower band gap is detected by DLTS measurement. This removes the opportunity of a pairing between phosphorus and platinum and suggests the possibility of a Fermi level controlled complex formation.

Co3O4 thin films were prepared via the Pechini method using spin-coating and sintering processes. X-ray diffraction (XRD), atomic force microscopy (AFM), and Raman spectroscopy were employed to characterize the films. The XRD pattern from the prepared films can be indexed based on a spinel structure. Ordered crystalline columns and high quality surfaces are observed via the AFM images. It is found out that the grain size increases with the sintering temperature. Minimum roughness of the film can be obtained at PEG content 60 mg/ml. Raman spectroscopy confirms that the films are crystallized in the spinel structure. A red shift observed in all bands shows that the cohesive energy is lower in the film than in the bulk crystal.

We report an in situ transmission electron microscopy (TEM) study of nanocavity evolution in amorphous Si (a-Si) under ion beam irradiation. The size evolution of the nanocavities was monitored during ion irradiation with Si or As at various temperatures between 300 and 600 K. A linear decrease of the nanocavity diameter was found as the ion fluence increased; it was much faster than its counterpart in crystalline Si (c-Si). Here, the shrinkage rate depended on the irradiation-induced atomic displacement rate. No significant temperature dependence was observed, confirming that the irradiation-induced nanocavity shrinkage in a-Si is essentially due to ballistic interactions, i.e., differs radically from that in c-Si. 


We present a systematic analysis, within the scope of electromagnetic theory, of the spectral moments method (SMM) and develop several ways to compute the linear response of any type of system. We show that the method can be used in diffraction studies regardless of the number, nature and form of the diffracting objects. Multiple diffraction is naturally taken into account in the computation. The method can thus be applied to determine propagation through any type of media. It is based on the computation of Green functions, solutions of discretized Maxwell's equations. Fourier transforms of Green functions are developed in continued fraction. Two approaches will be presented. In the first “global” approach, all space is discretized, the coefficients of continued fractions are computed directly from the dynamic matrix obtained by the discretization of Maxwell's equations and from sources and receivers. In the second “local” approach, only the diffracting system is discretized. This paper is devoted to the global approach. We study two important problems in electromagnetism, i.e. propagation of a plane wave through a heterogeneous layer and scattering of an isolated object. We present two computation techniques for plane wave propagation: one uses a small grid, is very rapid but the results are approximate; the other uses a large grid, is less rapid but the results are exact. We show that computing the reflectivity and/or transmissivity of photonic lattices is now a very simple problem. For scattering, we mainly report a series of tests on some canonical systems, such as cylinders or spheres, showing that SMM results are in very good agreement with the analytical results. Several types of absorbing boundary conditions are tested. We report results on backscattering cross-sections and the impulsional response of different one-, two- and three-dimensional systems.

The use of gettering techniques that can be precisely localized in the component, such as neutral element implantation, has become crucial for power device manufacturing. High-dose helium implantation in silicon with a subsequent annealing induces defects (cavities and dislocations) which are able to getter metallic impurities and interact with dopants. These interactions can become a drawback of this technique. In this work, Si wafers $\langle 111\rangle$-oriented, p-doped with a concentration in between 6 × 1014 and 8 × 1018 B/cm3, were used. Iron contamination was performed by backside implantation (100 keV and 1012 Fe cm−2). Helium implantation was performed at 40 keV and 5 × 1016 at cm−2 at room temperature and followed by a Furnace Annealing (FA) stage. Secondary Ion Mass Spectrometry (SIMS) was used to study the dopant/metal/cavity layer system. In this paper, we will focus on the cavity layer interactions with both metals and dopant impurities. Our experimental results exhibit a large segregation of both species within the cavity layer that occurs during the annealing stage. Both species segregate simultaneously in helium-implanted samples without interacting one to the other. The number of gettering sites does not limit the trapping reactions.