Carbon-related defects in Si:C/silicon heterostructures assessed by deep-level transient spectroscopy

This paper reports on a Deep-Level Transient Spectroscopy (DLTS) study of the electrically active defects in similar to 100 nm Si: C stressors, formed by chemical vapor deposition on p-type Czochralski silicon substrates. In addition, the impact of a post-deposition Rapid Thermal Annealing (RTA) at 850 degrees C on the DLT-spectra is investigated. It is shown that close to the surface at least two types of hole traps are present: one kind exhibiting slow hole capture, which may have a partial extended defect nature and a second type of hole trap behaving like a point defect. RTA increases the concentration of both hole traps and, in addition, introduces a point defect at EV + 0.35 eV in the depletion region of the silicon substrate at some distance from the Si: C epi layer. This level most likely corresponds with CiOi-related centers. Finally, a negative feature is found systematically for larger reverse bias pulses, which could point to a response of trap states at the Si: C/silicon hetero-interface

Shapiro steps in a superconducting film with an antidot lattice

Shapiro voltage steps at voltages V_n=nV_0 (n integer) have been observed in the voltage-current characteristics of a superconducting film with a square lattice of perforating microholes (antidots)in the presence of radiofrequent radiation. These equidistant steps appear at the second matching field H_2 when the flow of the interstitial vortex lattice in the periodic potential created by the antidots and the vortices trapped by them, is in phase with the applied rf frequency. Therefore, the observation of Shapiro steps clearly reveals the presence of mobile intersitial vortices in superconducting films with regular pinning arrays. The interstitial vortices, moved by the driving current, coexist with immobile vortices strongly pinned at the antidots.Comment: 6 pages text, 3 EPS figures, RevTeX, accepted for publication in PRB Rapid Communication

Study of electrically active defects in epitaxial layers on silicon

Electrically active defects in silicon-based epitaxial layers on silicon substrates have been studied by Deep-Level Transient Spectroscopy (DLTS). Several aspects have been investigated, like, the impact of the pre-epi cleaning conditions and the effect of a post-deposition anneal on the deep-level properties. It is shown that the pre-cleaning thermal budget has a strong influence on the defects at the substrate/epi layer interface. At the same time, a post-deposition Forming Gas Anneal can passivate to a large extent the active defect states. Finally, it is shown that application of a post-deposition anneal increases the out-diffusion of carbon from a Si:C stressor layer into the p-type CZ substrate

OMA - the Open Marine Archive for Flemish marine research: facts and figures

In December 2005, the VLIZ-library launched the Open Marine Archive OMA. The purpose was to give immediate and complete access to all the published results of Flemish researchers. The immediate success of this initiative was largely due to the active support of the marine research community itself. Each Flemish/Belgian marine scientist was and is invited to contribute to this digital marine archive and to post his own publications on the OMA website. Today, already more than 3300 titles can be read and downloaded from www.vliz.be/oma.The IMIS-database behind the OMA archive has been adapted to the requirements of the OAI-PMH protocols (Open Archives Initiatives - Protocol for Metadata Harvesting). Specialized search engines, such as Google Scholar, and harvesters like the AVANO harvester developed by IFREMER, can now retrieve the specific marine metadata fromOMA and display the Flemish literature records at the top of their results lists. The links provided in these search results lead the user directly to the full text paper on the VLIZ servers.Further developments for OMA will be the direct linking of Flemish marine records from the ASFA-database (Aquatic Sciences and Fisheries Abstracts) to the OMA-record, and the retrospective completion of literature cv’s of all Flemish marine researchers

Vortex configurations and critical parameters in superconducting thin films containing antidot arrays: Nonlinear Ginzburg-Landau theory

Using the non-linear Ginzburg-Landau (GL) theory, we obtain the possible vortex configurations in superconducting thin films containing a square lattice of antidots. The equilibrium structural phase diagram is constructed which gives the different ground-state vortex configurations as function of the size and periodicity of the antidots for a given effective GL parameter $\kappa^{*}$. Giant-vortex states, combination of giant- and multi-vortex states, as well as symmetry imposed vortex-antivortex states are found to be the ground state for particular geometrical parameters of the sample. The antidot occupation number $n_o$ is calculated as a function of related parameters and comparison with existing expressions for the saturation number $n_s$ and with experimental results is given. For a small radius of antidots a triangular vortex lattice is obtained, where some of the vortices are pinned by the antidots and some of them are located between them. Transition between the square pinned and triangular vortex lattices is given for different values of the applied field. The enhanced critical current at integer and rational matching fields is found, where the level of enhancement at given magnetic field directly depends on the vortex-occupation number of the antidots. For certain parameters of the antidot lattice and/or temperature the critical current is found to be larger for higher magnetic fields. Superconducting/normal $H-T$ phase boundary exhibits different regimes as antidots are made larger, and we transit from a plain superconducting film to a thin-wire superconducting network. Presented results are in good agreement with available experiments and suggest possible new experiments.Comment: 15 pages and 20 figure

Validation of the reasons for gambling questionnaire (RGQ) in a British population survey

Introduction. The aim of the study is to validate the five-dimensional structure of the Reasons for Gambling Questionnaire (RGQ) and to test the differences between different types of gamblers (i.e., offline gamblers who gambled in-person only vs.mixed-mode gamblers who gambled both online and offline) on the five dimensions of the RGQ. Methods. Data from the 2010 British Gambling Prevalence Survey (BGPS) were used. The analysed data comprised 5,677 individuals (52.7% female; mean age=47.64 years; SD=17.82). Confirmatory factor analysis and independent-samples t-tests were applied. Results. The five-dimensional structure of the RGQ wasconfirmed in the general sample and among gender and age subgroups. Furthermore, mixed-mode gamblers (MMGs) who gambled both online and offline had higher scores for enhancement, recreation and money motives than offline gamblers that gambled in-person only (IPGs). In addition among males, there was a significant difference in the scores for enhancement and recreation motives across MMGs and IPGs. Among past-year gamblers aged 16-34 years, MMGs had higher scores for enhancement, recreational and monetary motives than IPGs whilst among past-year gamblers aged 35-55years, MMGs had higher scores for enhancement and recreational motives than IPGs. Conclusions. The results are consistent with a previous test of the RGQ and the findings indicate that the RGQis a valid instrument to assess gambling motives among the general population

On Maximal Massive 3D Supergravity

We construct, at the linearized level, the three-dimensional (3D) N = 4 supersymmetric "general massive supergravity" and the maximally supersymmetric N = 8 "new massive supergravity". We also construct the maximally supersymmetric linearized N = 7 topologically massive supergravity, although we expect N = 6 to be maximal at the non-linear level.Comment: 33 page

More on Massive 3D Supergravity

Completing earlier work on three dimensional (3D) N=1 supergravity with curvature-squared terms, we construct the general supergravity extension of cosmological massive gravity theories. We expand about supersymmetric anti-de Sitter vacua, finding the conditions for bulk unitarity and the critical points in parameter space at which the spectrum changes. We discuss implications for the dual conformal field theory.Comment: v1 : 53 pages, 1 figure; v2 : significantly shortened, 42 p., version published in Class. Quant. Gra

On Critical Massive (Super)Gravity in adS3

We review the status of three-dimensional "general massive gravity" (GMG) in its linearization about an anti-de Sitter (adS) vacuum, focusing on critical points in parameter space that yield generalizations of "chiral gravity". We then show how these results extend to N=1 super-GMG, expanded about a supersymmetric adS vacuum, and also to the most general `curvature-squared' N=1 supergravity model.Comment: 10 pages, Proceedings of ERE 2010, Granada, 6-10 september 2010; reference adde