The very intense radiation environment of high luminosity future colliding beam experiments (LHC, etc.) makes radiation hardness the most important issue for Si detectors. The crucial question is whether the Si strip detectors can withstand the harsh radiation environment for sufficiently long time (full LHC lifetime) and hence the central issue concerning all LHC experiments is the breakdown performance of these detectors. In this paper the simulations have been performed to analyze electrical parameters for the most deleterious long-term effect of radiation: the change in effective charge carrier concentration and resulting increase in full depletion bias. Detailed calculations using Hamburg Model have allowed the parameterization of these effects, and helped to simulate the operation scenario of Si detectors over 10 years of LHC operation. The systematic studies of the electric field to get an insight into the device behavior provide, for the first time, a possible explanation for the improvement in breakdown performance with radiation. Simulation study is also carried on optimized guard ring structures to study the change in guard voltage distribution after 10 years of neutron radiation damage.

We have theoretically studied the electronic structure of Si δ-doped GaAs inserted into an infinite quantum well as dependent on the applied electric field. For the uniform distribution we have investigated the influence of the electric field on the donor distribution thickness as different from other authors. The present method is based on a self-consistent solution of the Schrödinger and Poisson equations. From our calculations, we have seen that a high applied electric field is significantly changed the subband structure of the δ-doped GaAs and the change of the electronic properties as dependent on the applied electric field is more pronounced at wide doping thickness. The high electric fields can induce a spatial separation between confined electrons and ionized dopants in the δ-doped GaAs structure resulting in enhanced free carrier mobility in semiconductor devices.

We have studied the well known spectral shift of polyfluorene blue light emitters, using either electrochemical cells or conventional organic light emitting diodes. From the recording of the electroluminescence spectra as a function of “stress” time, we conclude that the degradation mainly depends on the number of electrons which have passed through the conducting polymer, rather than on the hole current magnitude or the dissipated power.

A grooved plate matrix theory of a new high intensity magnetic separator is proposed. The results of the grooved plate devices yet reported, were only experimental. In the present paper, a theoretical approach is developed, in spite of the difficulties caused by the particular shape of the collectors, complicating the calculation of forces involved in the separation process. The work presented here, proposes the modeling used to study filtration efficiency in grooved matrix, for two models of fluid flow, as well as the results which were obtained. The range of validity of these models of fluid flow, applied to establish the matrix efficiency is discussed. The progressive saturation of the extraction matrix is also investigated. Good correspondence between theoretical results and experimental data is found.

The absorption and excitation spectra of the tetrahedrally coordinated Cr4+ ions doped in LiGaO2 oxide crystal are measured by Kück and Hartung at room temperature. Using the experimentally determined data from these spectra, a theoretical calculation for the crystal-field levels of Cr4+:LiGaO2 was performed by Kück and Hartung, based on the angular overlap model theory (AOM). The calculation reveals an important discrepancy between the theoretical and the experimental energies. A detailed crystal-field analysis of electronic energy levels of Cr4+ doped in LiGaO2 oxide crystal based on the Racah theory is proposed in this work. The observed crystalline-field splitting of the Cr4+ terms was accounted for using a C1 symmetric Hamiltonian. In turn, reliable crystal-field and Racah parameters have been obtained. This theoretical analysis confirms the observed crystalline-field splittings of the 3F and 3P terms of the Cr4+ ion doped in the oxide crystal LiGaO2.

We use High Resolution Electron Microscopy (HRTEM) together with Electron Energy Loss Spectroscopy (EELS) to analyze the crystallography and the chemical configuration of interfaces in a state-of-the-art La2/3Sr1/3MnO3/SrTiO3/La2/3Sr1/3MnO3 tunnel junction. EELS indicates that manganese ions keep their bulk valency up to the last atomic plane in contact with the insulator. Tunnel magnetoresistance however decreases with temperature faster than magnetisation in these samples. Quantitative HRTEM reveals some local departures from chemical abruptness at the interfaces, which could play a role in this decrease.

Among the existing non-destructive testing techniques, the flying spot photothermal technique [CITE] appears to be a good alternative to penetrant testing for open-cracks detection in metallic structures. The technique basically consists in the local heating of a structure under test and the measurement of the temperature elevation which depends on the inspected medium properties. During the scanning of the structure, thermal and optical effects contribute to the elaboration of the photothermal signals. The thermal effect is relative to the presence of a thermal barrier in the inspected medium (e.g. crack) and the optical effects are due to the variations of the absorptivity and diffusivity factors of the inspected surface (surface conditions). Both effects are competitive and can lead to hardly interpretable signals. In this paper, the authors present a method allowing to separately identify thermal and optical effects, in order to enhance the characterization of the structure under test. The method was applied on a mockup featuring open-cracks and rough surface conditions, and allows to construct separate optical and thermal images. The resulting so-called thermal image allows to significantly highlight the presence of the cracks. Besides, the optical image enriches the characterization of the structure, since it supplements the diagnosis of the cracks and also enables to characterize other defects such as surface topology and features.

It is well known that for a 2 dimensional hydrogenated amorphous silicon thin film position sensitive detector (a-Si:H TFPSD), the calculated coordinates of the position, from the currents measured on the PSD, do not represent the real spot position. The errors result from the generally used position-current expression, and also from device fabrication defects such as the inhomogeneity of TCO thickness and the electrode contact resistance. The best way to correct the errors is to calibrate the device. In this paper, we present a calibration method developed earlier for a smart pressure sensor to calibrate a 2D tetralateral a-Si:H TFPSD. The calibration algorithm is presented. Experimental results are shown and the calibration error is discussed.