- Published on 26 June 2009
In this paper we investigate theoretically a mode of heating thick layers using a laser beam where the temperature of the layer propagates in a steady-state self sustained fashion from the bottom of the layer towards the surface and may exhibit a very steep front. The propagation of the thermal front happens at a constant speed, related to the intensity of the power flux. To achieve this heating mode the absorption coefficient of the layer has to remain low in weak temperatures and increase rapidly as a function of temperature in higher temperatures. Additionally, a significant temperature increase must be generated to trigger this propagation mode, for example through the presence of a strongly absorbing layer beneath the transparent layer. The mode is well suited to semiconductors, especially silicon . The theoretical approach is confirmed by a simulation in the case of a low doped silicon layer 150 micrometers thick above a highly doped substrate ; the low doped silicon is heated homogeneously at 1476 K by a 2E6Wcm-2 CO2 laser beam throughought the entire thickness in a timescale of 20µS.
Photoinduced Switching of Charge Carrier Mobility in Conjugated Polymers, M. Weiter, J. Navrátil, M. Vala and P. Toman (2009), Eur. Phys. J. Appl. Phys. DOI 10.1051/epjap/2009112
- Published on 04 May 2009
EPJ launches EPJ Web of Conferences an open-access publishing service dedicated to the publication of conference proceedings and the related archiving of conference web pages. Maximum speed of publication and visibility are combined with a maximum of flexibility regarding formats.
For further information have a look at the website of EPJ Web of Conferences
- Published on 28 March 2009
The structural investigations of model organic systems like pentacene in the monolayer regime is very important for fundamental understanding of the initial nucleation process together with the electronic performance of transistor devices. The fact that the transistor performance saturates after deposition of some monolayers of the active organic material motivates a basic investigation of the submonolayer and monolayer regime in more detail. In this paper a method for the evaluation of the island formation and the island growth within the first monolayer is introduced. The method is based on X-ray scattering under grazing incident condition by means of specular X-ray reflectivity and off-specular X-ray scattering. From the specular reflectivity the electron density can be obtained which is directly correlated with the coverage of a submonolayer. Within the presented experiment coverages ranging from 7% up to 97% could be identified and are in excellent agreement with atomic force microscope results. Lateral information on the islands is obtained by rocking curve and detector scan measurements under grazing incident condition. The observed correlation peaks are evaluated by using Distorted Wave Born approximation, whereby mean island sizes ranging from 300nm to 1.5µm and mean island separation of about 2µm could be determined for the various samples. The obtained results encourages the use of this type of investigation for in-situ growth experiments to obtain a better understanding of the first monolayer formation.
Evaluation of organic sub-monolayers by X-ray based measurements under gracing incident conditions, O. Werzer, B. Satdlober, A. Haase, H.-G. Flesch and R. Resel (2009), Eur. Phys. J. Appl. Phys., DOI 10.1051/epjap/2009038
Laser heating of thick layers through a backwards, self-sustained propagation of a steep, steady state thermal front
- Published on 05 January 2009
Presented paper reports on switching device based on reversible modulation of charge carrier mobility by photochromic additive distributed in polymer matrix. The light induced photochromic conversion of the additive is accompanied by significant increase of its dipole moment. The presence of the dipole moment induces change of electrostatic potential in its vicinity and shifts the site energies of individual polymer repeating units. Since the position and orientation of the photochromic additive with respect to the polymer chain are essentially random the effect results in broadening of the distribution of the transport states and consequently in the lowering of the charge carriers mobility. These notions suggested by quantum chemistry modeling are proved by experimental characterization of the optical and electrical switching properties of the suggested switch. The observed current-voltage characteristics showed reversible decrease of the currents after the photochromic switching of the additive to its metastable state with high dipole moment. This behaviour was explained on the basis of charge carrier mobility decrease due to the presence of charge traps. Impedance spectroscopy revealed a drop of the bulk conductivity when the polar state of the photochromic molecules was present. The induced conductivity decrease is proportional to the drop observed by current-voltage characterization.
Laser heating of thick layers through a backwards, self-sustained propagation of a steep, steady state thermal front, Michel Bruel (2009), Eur. Phys. J. Appl. Phys. DOI 10.1051/epjap:2008190
- Published on 12 November 2008
Athene Donald, Professor of Experimental Physics at the Cavendish Laboratory in Cambridge, has been nominated for her contribution to unravelling the mysteries of the physics of messy materials, ranging from cement to starch. Some of this work was published in the EPJ E. The former editor in chief of EPJ E (and current member of its advisory editorial board) will receive her prize on 5 March 2009, at UNESCO Headquarters in Paris. Since 1998, the L'ORÉAL-UNESCO Awards have distinguished 57 women from around the globe. Through their individual contributions to scientific research the Laureates have been agents for change and progress. We have no doubt that Athene Donald will take this award as a new opportunity to promote the work and dedication of female scientists and inspire them to excel.
- Published on 03 November 2008
- Published on 06 October 2008
Following the completion of the first period (2007-2008) of its OA publishing scheme, and in anticipation of successful negotiations with interested Open Access funding agencies in the future, the "open access" publishing fees for all experimental papers submitted to and accepted for publication by The European Physical Journal C - Particles and Fields will continue to be waived. The paper categories concerned are both regular articles and scientific notes, on experimental physics. Independently, all Letters continue to be published "open access" by default, without any fees being incurred by the authors.
- Published on 01 September 2008
Prof. Georg Weiglein (University of Durham, UK) has been appointed the new Editor-in-Chief for theoretical particle and high-energy physics of The European Physical Journal (EPJ) C. He leads the journal into the hot phase of LHC physics and works together with Prof. Siegfried Bethke (MPI Munich, Germany), Editor-in-Chief for experimental physics. Georg Weiglein succeeds Jochen Bartels (University of Hamburg, Germany), who had been the journal's theory Editor-in-Chief since 1999. Jochen Bartels and Dieter Haidt (DESY, Hamburg) together successfully shaped the profile of EPJC, after the merger of the famous journals Zeitschrift für Physik C and Il Nuovo Cimento A, back in 1998.
- Published on 13 May 2008
Colloquia describe the development of new areas of research or the impact of new and promising experimental, theoretical or computational methods in the fields that are within the spectrum of topics covered by the journal. While not as extensive and complete as reviews in the usual sense, they are intended to suitably introduce new research directions and techniques in their early stages of development, and to a wider audience. There is no explicit constraint regarding the length of such manuscripts, although 20 printed pages would be the most usual length. All invited/submitted manuscripts will undergo the same refereeing procedure as all other contributions submitted to the journal. For accepted colloquium papers, authors will receive a honorarium of EUR 200,-- and colour figures will be free of charge. For more details on this new section in EPJD see the Editorial written by the Editors-in-Chief Claude Fabre and Franco A. Gianturco.
- Published on 02 May 2008
The publishers of The European Physical Journal B - Condensed Matter and Complex Systems are pleased to announce the appointment of Prof. Alois Loidl (U of Augsburg) and Prof. Luciano Colombo (U of Cagliari) as new Editors-in-Chief for experimental resp. theoretical condensed matter physics. At this occasion, EPJ B opens a new main section on computational methods which will publish papers on the theoretical development and numerical benchmarking of existing and new tools in scientific computing of relevance for computational solid state and materials physics. In particular, ab initio techniques, atomistic simulations, quantum monte carlo, and multiscale modelling will be in the new focus.