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The wood diseases are very damaging to the culture of citrus and many hosts around the world. It is considered as a complex pathosystem that requires the analysis of its various aspects. In this context, we conducted epidemiological and etiological studies. Our studies were conducted for four consecutive years (2017-2020) on 25 orchards from five localities in Algeria. The results of symptom diagnosis showed the presence of different categories of symptoms; these are the total and/or partial dieback. The examination of the cross-sections of infected wood showed the presence of different forms of inner necrosis. The isolations from the necrotic tissues of the infected trees put often in evidence the presence of a diversified fungal flora dominated by Botryosphaeriaceae fungi. We also recorded an overall infection rate of 23.28% representing a severity index of 1.77 on a scale of four degrees, giving an incidence of 10.76%. The overall assessment of the dieback situation in the studied orchards showed a rapid increase in all epidemiological indices. The statistical analyzes showed that the factors region, age, rootstock, type of irrigation and soil texture had a highly significant effect on the variation of epidemiological parameters. However, the factor year is only moderately significant. On the other hand, the factor cultivar, has no significant effect on these indices. The epidemiological behavior of dieback in these orchards confirms that the spread of the disease is favored by cultural techniques such as irrigation and pruning.

The temporal technique analysis by a simplex optimization method of isothermal transient depolarization current measurements (Simplex-TSDC) is presented for the study of the glass transition domain of different polymers. The advantage of the present method compared to the classical TSDC is that it gives direct results comparable to the experiment and allows a good estimate of the relaxation time close to the glass transition temperature in dielectric thin films. The present method also allows a direct determination of two relaxation times corresponding to a fast and a slow dynamics; and then confirms the heterogeneous character of the molecular relaxation dynamics.

Relaxation times of bisphenol A polycarbonate around the glass transition temperature are estimated using the combination of differential scanning calorimetry (DSC) and thermostimulated depolarization currents (TSDC). These measurements are performed using samples with different thermal histories below and above the vitrification transformation. This protocol enables the extension of the range of equilibrium relaxation times measured by dielectric spectroscopy. By this mean we may recalculate the values of the Kauzmann temperature and fragility index.

The influence of a weak magnetic field on the electric current across silicon P+N junctions has been studied. The theoretical analysis considers two types of diodes: diodes with short base and diodes with long base and the magnetic field is assumed to be perpendicular to the direction of the electric current across the junction. The results show that the variation of the current is directly related to the variation of the hole diffusion coefficient, which is then calculated in the approximation of a P-type silicon material. The relative variation of the diffusion coefficient was found B2 dependent. Experimental investigations have then been carried out in order to validate the theoretical calculations. The experimental results were in good agreement with the theoretical development when taking into account the two types of holes in the diffusion mechanism in silicon.

International audience; Low-energy implantation is one of the most promising options for ultrashallow junction formation for the new generation of bipolar complementary metal oxide semiconductor (BiCMOS) silicon technology. Boron is one of the dopants to be implanted, but is the most problematic because of its low stopping power, and its tendency to undergo transient enhanced diffusion and clustering during thermal activation. In this paper we report an experimental contribution, using secondary defect profiles, to the understanding of low-energy B implants in crystalline silicon. Shallow p+n junctions were formed by low-energy B implantation – 1015 cm-2 at 3 KeV – into n-type crystalline silicon preamorphized with germanium – 1015 cm-2 at 30 KeV, 60 keV and 150 keV. Rapid thermal annealing (RTA) for 15 s at 950°C was then performed to achieve electrical activation of the dopant and implantation damage removal. We propose a reliable approach to the measurement of secondary defect profiles, induced by this process, using isothermal transient capacitance associated with deep-level transient spectroscopy (DLTS). This approach could be generalised to the profile measurement of any defect detected into silicon or III–V semiconductor substrate. In our case, we obtain a relatively high concentration of B-related electrically active defects to a depth of 3.5 µm in the crystalline silicon bulk.

In this paper, we propose an underactuated robotic finger whose grasp behavior is modulated by the design of its superelastic joints. Using shape-memory alloy, the finger joints can be given specific stiffness and pre-form shapes such that a single-cable actuation rather than opposing-pair actuation can be used; this also allows the grasping motions of the phalanges to be synchronized in the free phase and then adaptive once contact is made. A default-closed pre-tensioned configuration allows grasp forces to be maximal for larger objects and still keeps control components such as tendons out of the grasp workspace. The simplicity of the design lends itself to the possibility of integrated joint angle and surface pressure sensing on the finger itself. The details of design, prototyping and testing are described.

International audience; The Nelder–Mead simplex algorithm improved by Lagarias for low-dimension functions is introduced for the first time on transient capacitance signal analysis to decrease noise sensitivity and increase the resolution of deep-level transient spectroscopy method (DLTS). The application of the resolution figure of merit in predetermining the success of DLTS analyses' ability to resolve defects has shown that the performances of the simplex-DLTS developed in this work are significantly better than those of matrix pencil-DLTS method (MP-DLTS) published in 1998. Comparing experimentally the two methods in analyzing the signals generated by the same 150 keV germanium preamorphized p+n samples, we found that the simplex-DLTS method detects six defects in which some show very close activation energy values, while the MP-DLTS method found only two defects. Hence, the superiority of the simplex-DLTS method is proved; it reveals deep levels in which the emission process is carried out in the same temperature range.

As material quality improves and growth technology develops, SiC BJTs are regaining interest. They have the advantage of carrier modulation, high current capabilities and lower initial voltage drop. In this work, the thermal behaviour of 6H–SiC bipolar transistors is simulated. The examined figures of merit such as input resistance h 11 , current gain β and transconductance g m show superior performance of 6H–SiC BJTs, at high temperatures, when compared to similar silicon counterparts. In the range of temperatures −20 to 160 °C, drawbacks found in Si BJTs are attenuated or eliminated with the use of SiC BJTs. These advantages are transferred to 6H–SiC based circuits. The built current mirror shows quasi-ideal behaviour while the designed input stage of the amplifier has a voltage gain thermally stabilised up to 140 °C.

The increased requirements for reduction of electronic system dimensions, essentially in embedded equipment such as automotive and avionics, lead to juxtapose high power modules and low level modules on the same printed circuit. This juxtaposition induces electromagnetic perturbations that can disturb or damage the operation of the system. In order to study thoroughly these phenomena, a low frequency (LF) magnetic field was applied to shallow P+N junctions obtained by the preamorphization technique, at two temperatures: ambient and nitrogen temperature. Electrical characterizations were performed on the different samples. The results show that the impact of the LF magnetic field is essentially observed in the generation-recombination region of the junction. Moreover, it appears that crystalline sample presents a good immunity to the LF magnetic field perturbation at high temperature. On the other hand, the preamorphization temperature influences the response of the sample. So, a good control of the technological parameters will permit to reduce or cancel the effect of the magnetic perturbations on the electronic components since conception.

Shallow P + N junctions were obtained using germanium pre-amorphization step to reduce the high diffusivity of boron implanted in silicon. The germanium implantation step was performed under different conditions of temperature: ambient temperature and nitrogen temperature. P-type doping was obtained by boron implantation at relatively low energy. To characterize and simulate the electrical behaviour of such samples, steady state current–voltage measurements have been performed at different temperatures varying between 172 and 294 K. The results show a close dependence between the current–voltage characteristics of the samples and their technological parameters of manufacturing. The pre-amorphization step at ambient temperature seems to improve the electrical behaviour of the junction. To simulate the electrical characteristics of the studied samples, a reliable model has been developed based on the classical Spice formulas and taking into account additional phenomena. The simulated curves satisfactorily fit the experimental results for all the samples.

A method of characterization without contact of passive microstructures is presented in this paper. Samples of different SiO 2 -Au microcantilevers (lengths from 100μm to 300μm, width 40μm, thickness 1.1μm) were studied by means of a Michelson interferometer. Two measurement techniques were employed, one by impulse response and the other by synchronous detection, in order to obtain the microcantilevers Eigen resonant spectrum and thus to determine their first three resonant frequencies. The knowledge of these frequencies makes possible the determination of the Young’s modulus of material and thus simplifies the modeling of the microsystem.

There currently exists many optoelectronic methods of characterization of microstructures. We present here a dynamic method which uses the principle of the optical vibrometer in order to determine the oscillatory modes of microstructures. This measurement makes it possible to go up with the mechanical properties. It is a method without contact, based on the lighting of a microstructure using a laser beam guided by a lensed tapered optical fiber which will be used. Principal evolution of this technique is its miniaturization. It allows to integrate the device within a cryostat, where we will be able to carry out measurements with a control of temperature, pressure and composition of the atmosphere.

Germanium implantation into silicon substrate is currently used to preamorphisize the crystalline structure in order to avoid boron channeling effects in shallow P+N junction manufacturing. Nevertheless, after boron doping and rapid thermal annealing, different defects are formed within the structure, such as end of range defects which are created at the amorphous/crystalline interface. Our study concerns two types of shallow P+N junctions. These junctions were fabricated using low energy boron implantation at 3 KeV with a dose of 2×1015 cm-2 into high-energy germanium preamorphized n-type crystalline silicon substrates at 2.2 MeV with a dose of 1015 cm-2. In the first type, the preamorphization was performed at ambient temperature. In the second, the preamorphization was performed at liquid nitrogen temperature. Boron doping was followed by a Rapid Thermal Annealing (RTA) step for 15 s at 950 °C. Deep Level Transient Spectroscopy (DLTS) technique was used to characterize the defects formed in each structure. The impact of an ac magnetic field on the reverse current has been studied at a given bias, when sweeping the sample temperature. The measurements were performed under a low frequency (less than 1 kHz) magnetic field of a Vrms value of 2000 G, with sample temperature varying between 80 and 260 K. The results show a high activity of defects at low frequencies (1 and 10 Hz) for the nitrogen preamorphized sample. Moreover, this activity is observed at about 200 K which corresponds to the peak of the DLTS spectra of such sample. However, the ambient preamorphized sample characterized by a lower concentration of defects seems to be insensitive to the ac magnetic field. Therefore, it appears that the preamorphization-induced defects influence strongly the response of the junction to an applied ac magnetic field.

It is well established that low energy B+ ion implantation into Ge- (or Si) implantation pre-amorphised silicon allows ultra-shallow p+n junctions formation. However, this process is known to generate defects such as dislocation loops, vacancies and interstitials which can act as vehicles to different mechanisms inducing electrically active levels into the silicon bulk. The junctions studied have been obtained using 3 keV/ 10 15 cm −2 B + implantation into Ge-implantation pre-amorphised substrates and into a reference crystalline substrate. Accurate measurements using deep level transient spectroscopy (DLTS) and isothermal transient capacitance ΔC(t,T) were performed to characterise these levels. Such knowledge is crucial to improve the device characteristics. In order to sweep the silicon band gap, various experimental conditions were considered. The analysis of DLTS spectra have first showed three deep levels associated to secondary induced defects. Their concentration profiles were derived from isothermal transient capacitance at depths up to 3.5 μm into the silicon bulk and allowed us to detect a new deep level. The evolution of such defect distribution in correlation with the technological steps is discussed. The end of range (EOR) defect influence on electrical activity of secondary induced defects in ultra-shallow p+n diodes is clearly demonstrated.