Using the perturbation method (Born approximation), a theoretical model hasbeen developed to account for the EBIC intensities and contrasts likely to occur in ann-type polycrystalline semiconductor, as a function of the grain size. The influenceof the minority charge carrier diffusion length and the primary electron beam energyhave also been examined, respectively.

Be diffusion during post-growth annealing has been investigated in InGaAs epitaxiallayers. Kick-out mechanisms considering species charges, built-in electric field andFermi-level effect have been studied. Several forms of kick-out mechanism have beenimplemented in our simulation programs. Experimental concentration profiles obtainedby SIMS analysis have been compared systematically with the numerical results ofsimulations. We have deduced that the kick-out mechanism Bei 0 ↔ Bes − + IIII + is the dominating diffusion mechanism in InGaAsunder our experimental conditions (C 0 = 3 × 19 cm−3). With our experimentaldata, we have found that the effective diffusion coefficient values areD = (7.7−9) × 10−13 cm2 s−1 at T = 700 °C and D = (1.4−1.5) × 10−11 cm2 s−1 at T = 800 °C which is severalorders of magnitude higher than most published data. A possible explanation would bethe effect of V/III flux ratio.

This study reports on Be diffusion in InGaAsP layers grown by gas source molecularbeam epitaxy. The experimental structures consisted of a 2000 Å Be-doped(3 × 109 cm−3) In0.73Ga0.27As0.58P0.42 layersandwiched between two 5000 Å undopedIn0.73Ga0.27As0.58P0.42 layers. The samples were subjected to rapidthermal annealing in the temperature range from 700 to 900 °C with timedurations of 10 to 240 s. Secondary ion mass spectrometry was employed for aquantitative determination of the Be depth profiles. Concentration profiles of Be inInGaAsP have been simulated according to two kick-out models: the first modelinvolving neutral Be interstitials and singly positively charged Ga, Inself-interstitials, and the second model involving singly positively charged Beinterstitials and doubly positively charged Ga, In self-interstitials. Comparison withexperimental data shows that the first kick-out model gives a better description.

The thermodynamic theory developed in [1] is extended to describe the uniaxialstress induced cubic-tetragonal martensitic transformation. The theory is found toprovide a good quantitative agreement with the experimentally observed σ − T phase diagram of martensitic transformation exhibited by Ni–Mn–Ga alloys (σis the uniaxial compressive stress in [110] direction).

The use of a self-processing dry photopolymer layer capable of memorizing optical information as a local change in thickness, is proposed for the fabrication ofmicrolenses, binary holograms and gratings. Relief micro-optical elements aregenerated by direct imagewise exposure through a mask. A gradient of chemicalcomposition and a gradient of surface free energy cause the transfer of reactivespecies between dark and illuminated areas. Contrary to conventional lithographictechniques that require wet chemical post-treatment to remove parts of the photoresistmaterial, the fully self-processing character of this technique makes the recordavailable in situ and immediately after exposure.

Sn-doped indium oxide (ITO) films have been investigated for fast rise time laser pulse detection for the first time. The detector was tested for different wavelengths in the UV (280 nm, resulting in inter-band transitions of electrons) and NIR (1.06 μm, resulting in free carrier absorption) region. Characteristics of laser induced voltages for the ITO films with different compositions have been studied for both excitation wavelengths. The voltage pulse generated by NIR-excitation was delayed in time at least by 100 ns as compared with that generated by UV-excitation. Responsivity of the films is larger for the UV-excitation than for the NIR-excitation.

This article investigates the electronic transport properties of ZnO/ CdS/ Cu(In,Ga)Se2heterojunction solar cells during and after illumination or forward bias in the dark.We observe a relaxation of the open circuit voltage under constant illumination as wellas a relaxationof the voltage drop over the device under constant forward biascurrent in the dark. Both phenomena are accompanied by an increase of the samplecapacitance. We introduce a general quantitative model concept for the open circuitvoltage relaxation and related effects in heterojunction devices that explains thephenomena as a consequence of the persistent capture of charge carriers within thespace charge region. We apply our concept to develop a specific quantitative model forthe observed metastablity in Cu(In,Ga)Se2 heterojunction solar cells.

The generation and the behavior of amorphous hydrogenated carbonparticulates have been investigated in a pure methane low pressureradiofrequency discharge at 13.56 MHz. In the plasma, theformation and the presence of two kinds of particulateshave been evidenced by use of laser light scattering. The studyof the different forces acting on the particulates allowed us tounderstand their behavior in the discharge. Optical emission measurements have enabled us to correlate theevolutions of the emission lines (CH, Hα and H2)with the growth of amorphous hydrogenated carbon particulates andalso with the results obtained by laser light scattering. Theparticulate sizes have been measured and aparticulate number density of about 3.0 × 106 cm−3 has been determined.

A spectroscopic study of the GTAW plasma-plume created during the welding of stainless steel and other materials (iron, nickel and chromium) has been carried out. The spectra of these plasmas have been studied for several welding parameters. Temperature calculations are based on the observation of relative intensities and shapes of the emission peaks. We assume that the plasma is in local thermal equilibrium. The temperature is calculated with the Boltzmann plot method from twelve iron emission lines (in the range 368–385 nm): it varies between 9650 and 12100 K. Dilution experiments have been carried out. We checked the mixing of metals: during welding of two different metallic plates and during welding with an Inconel wire. Dilution is monitored following the intensity of some characteristic emission lines (chromium and nickel). Comparison of spectroscopic results and metallographic ones is made.

A method is proposed to determine the thermal effectiveness of heat exchangers in situ, when one of the fluids is submitted to any kind of flow rate variations. It leads to the definition of the average effectiveness in unsteady state, which forms an extension of the classical effectiveness used in steady state. It requires an unsophisticated equipment of measurement and should lead to an easy and continuous control of the fouling of heat exchangers.

The echo attenuation function EΔ (q) and the displacement probability P(Z,Δ) for water flowing through a bed of 0.3 mm glass beads has been measured by means of Pulsed Gradient Spin Echo (PGSE NMR). The encoding time Δ and the flow rates usedin the experiments were chosen such that the average displacement was at least one beaddiameter. The EΔ (q) shows, as expected, a diffraction peak at about the inverse ofthe bead diameter. For longer times EΔ (q) shows another peak at about the inverse oftwice the bead diameter. In analogy with PGSE NMR in presence of diffusion in a closedsystem, these data suggest that the pore space correlation function or featuresclosely related to it, can be accessed through the PGSE experiment with flow. Theconditions, which lead to this possibility, are discussed and supported with theresults of network modelling of fluid flow in a periodic structure. The true porespace correlation function has been determined using the Patterson function approachapplied to a NMR image data set. This has been compared with the one obtained by PGSENMR with flow. The displacement distributions P(Z,Δ) for fluid flow/diffusion in thissystem also show structural information and, it is suggested, can be regarded as aproduct of the pore space correlation function with an evolving smooth distributionwhich starts as an exponential and tends to a Gaussian in the longer time limit.

We studied the response of vascular endothelial cells to unidirectional laminar flow through collapsed veins. An original experimental set-up was developed, to generate and to map shear stresses with local transverse gradients. This enabled us to detect changes in the shape of endothelial cells when viscous fluid flow was applied. Porcine vena cava endothelial cells were seeded on a proof sample placed in the specifically designed flow chamber. Postconfluent endothelial cells were continuously exposed to a maximum calculated wall shear stress of 0.11 Pa (1.1 dyne/cm2) and to a maximum calculated transverse gradient of 0.045 Pa/mm for 20 hours. This paper deals with the morphometry of single cells and the angle of their major axes with respect to the flow direction. Cells in confluent monolayer underwent a shear stress intensity-dependent change in shape with a decrease of shape index from 0.55 to 0.34. The cells were not uniformly oriented in the direction of flow axes except in the region of larger gradient. In this particular region, the cells had a low angle with respect to the flow axes at some coordinates or exhibited reversal of their major and minor axes with a doubling of cell area. These observations suggest that there have been specific cytoskeleton rearrangements, associated with specific resultant forces over the cellular surface.