Technologies Avancées

Growth of grains effect on boron diffusion in heavily doped LPCVD polysilicon thin films

2018-12-06T09:57:13+00:00

In this study, we propose a two stream diffusion model adapted to the granular structure of polysilicon and to the effects of high-concentrations. This model takes into account temporal and thermal changes of the morphological structure of polysilicon by the grains growth during post-implantation annealing. The dopant trapping and segregation effects were combined with those of complex phenomena related to the strong concentrations such as clustering and exceeds of the solubility solid limit. This will permit to understand more exactly the significant role of the grains growth effect for the precise determination of the diffusion profiles. The adjustment of simulated profiles with the experimental SIMS profiles for short annealing times ranging between 1 and 15 minutes at the temperature of 850°C allowed the validation of this model. Grains growth and boron clustering are the major effects for the precise simulation of the diffusion profiles. The dominant mechanism of boron transfer to the grain boundaries is grains growth during which the grain boundaries collect boron by the trapping and segregation mechanism.

Keywords: boron, diffusion, model, grains, grain boundaries, polysilicon.

Technologies Avancees Vol. 18 2006: pp. 5-11

Microwave Correlation Measurement Crossed-pair Antennas Techniques Diagnosis of Breast Cancer

2018-12-06T09:57:13+00:00

Microwave correlation radiometry is a possible alternative technique to multi-frequency radiometry for obtaining a measurement of the subcutaneous temperature gradient in living tissue. In its simplest form this technique consists of combining the outputs of two antennas feeding a microwave correlation radiometer. Microwave correlation is based on the coherent detection of noise, here presented as the correlated signal from the two antennas. We propose here new processes, an add and square correlation radiometer and the non-resonant perturbation, which thoroughly investigated for different muscle phantom materials to define the optimum penetration depth of the electromagnetic field at fixed distance between the antennas.

Keywords: Microwave correlation radiometer, non-resonant perturbation, Medical application

Technologies Avancees Vol. 18 2006: pp. 12-17

Analysis of Rectangular Microstrip Antennas with Air Substrates

2018-12-06T09:57:13+00:00

This paper presents an analysis of rectangular microstrip antennas with air substrates. The effect of the substrate thickness on the bandwidth and the efficiency are examined. An additional thin layer supporting the dielectric material is added to the air substrate in order to make the antenna mechanically rigid and easy to manufacture. The effect of the dielectric material, of this additional substrate layer and its thickness on the antenna characteristics, is investigated. The thin dielectric material is then inverted so that the patch is deposited on its lower side in order to protect the metal from the surrounding environment.

Keywords: microstrip antennas – air substrate – thickness – foam material – inverted patch – bandwidth – efficiency – return loss.

Technologies Avancees Vol. 18 2006: pp. 18-22

Contribution to the improvement of control strategies

2018-12-06T09:57:13+00:00

In this work, a comparative survey will be done among three control strategies to determine the compensation current in a shunt active filter. We have introduced a fuzzy regulator for each strategy to improve the DC capacitor voltage response. The first one is based on the PQ theory proposed by Akagi et al., in 1983. In the second strategy, the average power is calculated and divided equally between the three phases. The third method consists of calculating the instantaneous and average powers of the load. Simulation results will be used to compare the performance of the control strategies.

Keywords: Shunt active filter, PQ theory, Fuzzy logic, PI regulator.

Technologies Avancees Vol. 18 2006: pp. 23-27

Impact des NTIC sur les acteurs de la Supply Chain

2018-12-06T09:57:13+00:00

L'utilisation des Nouvelles Technologies de l'Information et de la Communication (NTIC) dans les milieux industriels a changé certaines données et certains comportements, aussi bien dans les processus internes des entreprises, que dans les relations inter-entreprises. Désormais incon¬tournables, ces technologies sont cependant de plus en plus complexes. Entre nécessité et complexité des NTIC, les entreprises ont du mal à juger et à quantifier leur contribution. Nous proposons dans cet article d'évaluer l'apport de ces technologies ainsi que leurs freins et limites dans le cadre d'une problématique d'entreprises en réseau, en nous intéressant particulièrement à leur utilisation dans les chaînes logistiques (Supply Chain).

Keywords: NTIC, Supply Chain Management (SCM), Réseau d'entreprises, Intégration, Collaboration, Coordination.

Technologies Avancees Vol. 18 2006: pp. 28-39