Dirigisme, politique industrielle et rhétorique industrialiste

Le dirigisme économique français relève de ces évidences peu discutées aussi bien par les acteurs que dans la littérature. Pourtant, une étude empirique systématique des politiques publiques industrielles montre que, hors le cas des « grands projets » où sont mobilisés par un Etat de passe-droit la commande, la recherche, le financement et l'entreprise publics au service d'objectifs de souveraineté, les politiques industrielles relèvent en fait de l'accompagnement de stratégies d'entreprises ou de la recherche de la paix civile. La mise en perspective historique n'infirme pas ce résultat, elle révèle des configurations contrastées de relations Etat-Industrie où l'administration économique agit davantage sur l'environnement de l'entreprise qu'elle ne pèse sur les orientations sectorielles des acteurs. Dès lors, la logique partiellement autonome de la rhétorique industrialiste devient objet d'étude

Использование принципа клиентоориентированности при формировании стратегии развития предприятий

Материалы межвуз. науч. конф. студентов, магистрантов и аспирантов, Гомель, 15 мая 2008 г

On-axis homoepitaxial growth on Si-face 4H–SiC substrates

Homoepitaxial growth has been performed on Si-face nominally on-axis 4H–SiC substrates using horizontal Hot-wall chemical vapor deposition system. Special attention was paid to the surface preparation before starting the growth. In-situ surface preparation, starting growth parameters and growth temperature are found to play a vital role to maintain the polytype stability in the epilayer. High quality epilayers with 100% 4H–SiC were obtained on full 2″ substrates. Different optical and structural techniques were used to characterize the material and to understand the growth mechanisms. It was found that the replication of the basal plane dislocation from the substrate into the epilayer can be completely eliminated. The on-axis grown epitaxial layers were of high quality and did not show surface morphological defects, typically seen in off-axis grown layers, but had a high surface roughness.Original publication: J. Hassan, J.P. Bergman, A. Henry and E. Janzén, On-axis homoepitaxial growth on Si-face 4H–SiC substrates, 2008, Journal of Crystal Growth, (310), 20, 4424-4429.http://dx.doi.org/10.1016/j.jcrysgro.2008.06.081. Copyright: Elsevier B.V., http://www.elsevier.com

Epitaxial growth on on-axis substrates

SiC epitaxial growth using the Chemical Vapour Deposition (CVD) technique on nominally on-axis substrate is presented. Both standard and chloride-based chemistry have been used with the aim to obtain high quality layers suitable for device fabrication. Both homoepitaxy (4H on 4H) and heteroepitaxy (3C on hexag onal substrate) are addressed

Epitaxial growth on on-axis substrates

SiC epitaxial growth using the Chemical Vapour Deposition (CVD) technique on nominally on-axis substrate is presented. Both standard and chloride-based chemistry have been used with the aim to obtain high quality layers suitable for device fabrication. Both homoepitaxy (4H on 4H) and heteroepitaxy (3C on hexag onal substrate) are addressed

The role of boron related defects in limiting charge carrier lifetime in 4H-SiC epitaxial layers

One of the main challenges in realizing 4H-SiC (silicon carbide)-based bipolar devices is the improvement of minority carrier lifetime in as-grown epitaxial layers. Although Z1/2 has been identified as the dominant carrier lifetime limiting defect, we report on B-related centers being another dominant source of recombination and acting as lifetime limiting defects in 4H-SiC epitaxial layers. Combining time-resolved photoluminescence (TRPL) measurement in near band edge emission and 530 nm, deep level transient spectroscopy, and minority carrier transient spectroscopy (MCTS), it was found that B related deep levels in the lower half of the bandgap are responsible for killing the minority carriers in n-type, 4H-SiC epitaxial layers when the concentration of Z1/2 is already low. The impact of these centers on the charge carrier dynamics is investigated by correlating the MCTS results with temperature-dependent TRPL decay measurements. It is shown that the influence of shallow B acceptors on the minority carrier lifetime becomes neutralized at temperatures above ∼422 K. Instead, the deep B related acceptor level, known as the D-center, remains active until temperatures above ∼570 K. Moreover, a correlation between the deep level concentrations, minority carrier lifetimes, and growth parameters indicates that intentional nitrogen doping hinders the formation of deep B acceptor levels. Furthermore, tuning growth parameters, including growth temperature and C/Si ratio, is shown to be crucial for improving the minority carrier lifetime in as-grown 4H-SiC epitaxial layers.ISSN:2166-532

Carrier Lifetime Controlling Defects Z(1/2) and RB1 in Standard and Chlorinated Chemistry Grown 4H-SiC

4H-SiC epilayers grown by standard and chlorinated chemistry were analyzed for their minority carrier lifetime and deep level recombination centers using time-resolved photoluminescence (TRPL) and standard deep level transient spectroscopy (DLTS). Next to the well-known Z(1/2) deep level a second effective lifetime killer, RB1 (activation energy 1.05 eV, electron capture cross section 2 x 10(-16) cm(2), suggested hole capture cross section (5 +/- 2) x 10(-15) cm(2)), is detected in chloride chemistry grown epilayers. Junction-DLTS and bulk recombination simulations are used to confirm the lifetime killing properties of this level. The measured RB1 concentration appears to be a function of the iron-related Fe1 level concentration, which is unintentionally introduced via the corrosion of reactor steel parts by the chlorinated chemistry. Reactor design and the growth zone temperature profile are thought to enable the formation of RB1 in the presence of iron contamination under conditions otherwise optimal for growth of material with very low Z(1/2) concentrations. The RB1 defect is either an intrinsic defect similar to RD1/2 or EH5 or a complex involving iron. Control of these corrosion issues allows the growth of material at a high growth rate and with high minority carrier lifetime based on Z(1/2) as the only bulk recombination center.Funding Agencies|The Swedish Energy Agency; Swedish Research Council (VR); Swedish Foundation for Strategic Research (SSF); LG Innotek</p