11,815 research outputs found
Recombination activity of iron-gallium and iron-indium pairs in silicon
The recombination activity of iron-gallium (FeGa) and iron-indium (FeIn) pairs in crystalline silicon is studied by means of injection-dependent carrier lifetime measurements on Fe-implanted, Ga- and In-doped p-type silicon wafers of different resistivities (0.3–15Ωcm). Compared to FeB pairs, FeGa and FeIn pairs are found to be much more effective recombination centers in p-type silicon. Using Shockley–Read–Hall statistics we determine the energy level Et of the FeGa-related center to be 0.20eV above the valence-band edge Eν. The strong recombination activity of FeGa is assigned to its large electron-capture cross section σn of 4×10⁻¹⁴cm². The hole-capture cross section σp is 2×10⁻¹⁴cm². For the FeIn-related recombination center, our measurements show that Et=Eν+0.15eV, σn=3.5×10⁻¹³cm², and σp=1.5×10⁻¹⁴cm². Strong illumination with white light is found to dissociate both types of pairs. Storage of the samples in the dark leads to a full repairing of FeGa and FeIn pairs. Lifetime changes measured before and after illumination can be used to determine the interstitialiron concentration in Ga- and In-doped silicon using calibration factors determined from the measured defect parameters.J.S. thanks A. Cuevas and A. Blakers for their hospitality
during his research stay at ANU and acknowledges the financial
support of the Alexander von Humboldt Foundation.
D.M. acknowledges the financial support of the Australian
Research Council
Fusion mechanism in fullerene-fullerene collisions -- The deciding role of giant oblate-prolate motion
We provide answers to long-lasting questions in the puzzling behavior of
fullerene-fullerene fusion: Why are the fusion barriers so exceptionally high
and the fusion cross sections so extremely small? An ab initio nonadiabatic
quantum molecular dynamics (NA-QMD) analysis of C+C collisions
reveals that the dominant excitation of an exceptionally "giant" oblate-prolate
H mode plays the key role in answering both questions. From these
microscopic calculations, a macroscopic collision model is derived, which
reproduces the NA-QMD results. Moreover, it predicts analytically fusion
barriers for different fullerene-fullerene combinations in excellent agreement
with experiments
Authorised Translations of Electronic Documents
A concept is proposed to extend authorised translations of documents to
electronically signed, digital documents. Central element of the solution is an
electronic seal, embodied as an XML data structure, which attests to the
correctness of the translation and the authorisation of the translator. The
seal contains a digital signature binding together original and translated
document, thus enabling forensic inspection and therefore legal security in the
appropriation of the translation. Organisational aspects of possible
implementation variants of electronic authorised translations are discussed and
a realisation as a stand-alone web-service is presented.Comment: In: Peer-reviewed Proceedings of the Information Security South
Africa (ISSA) 2006 From Insight to Foresight Conference, 5 to 7 July 2006,
Sandton, South Afric
BeSpaceD: Towards a Tool Framework and Methodology for the Specification and Verification of Spatial Behavior of Distributed Software Component Systems
In this report, we present work towards a framework for modeling and checking
behavior of spatially distributed component systems. Design goals of our
framework are the ability to model spatial behavior in a component oriented,
simple and intuitive way, the possibility to automatically analyse and verify
systems and integration possibilities with other modeling and verification
tools. We present examples and the verification steps necessary to prove
properties such as range coverage or the absence of collisions between
components and technical details
Contingency learning tracks with stimulus-response proportion no evidence of misprediction costs
We investigate the processes involved in human contingency learning using the color-word contingency learning paradigm. In this task, participants respond to the print color of neutral words. Each word is frequently presented in one color. Results show that participants respond faster and more accurately to words presented in their expected color. In Experiment 1, we observed better performance for high-relative to medium-frequency word-color pairs, and for medium-relative to low-frequency pairs. Within the medium-frequency condition, it did not matter whether the word was predictive of a currently-unpresented color, or the color was predictive of a currently-unpresented word. We conclude that a given word facilitates each potential response proportional to how often they co-occurred. In contrast, there was no evidence for costs associated with violations of high-frequency expectancies. Experiment 2 further introduced a novel word baseline condition, which also provided no evidence for competition between retrieved responses
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