Incubation Time Measurements in Thin-Film Deposition

Studies on the initial growth or nucleation of materials and research on selective deposition often mention an incubation time. Many techniques exist to determine the incubation time. The outcome can be very different for each technique when the same nucleation process is considered. For the first time we have given a simple model which shows that several incubation times can be expected if different methods are used. One of the most popular methods, plotting the mass or thickness as a function of time and defining the incubation time as the intercept on the x-axis, is not a good method. In particular, a meaningful incubation time is found only if a layer-by-layer growth mechanism occurs right from the start. Ellipsometry can be used in situ and is a much more sensitive method, but this technique needs more research to correlate the nucleation process with the data obtained using this technique. The determination of the nucleus density using scanning electron microscopy or atomic force microscope is the most accurate method, yet needs a lot of experiments. Without a detailed description of the measurement method the incubation time is a meaningless quantity

Coupling currents in Rutherford cables under time varying conditions

A network model is presented to simulate fully transposed Rutherford cables under time varying conditions. The intrinsic properties of the cable and the external applied conditions can be changed spatially. Several statistical distributions of the contact resistances are built in to investigate local differences in the coupling loss and in the eddy currents. The average loss is quite independent of the resistance distribution but locally both the loss and the eddy currents can increase significantly. The self field distribution of the cable is included, resulting in a saturation of the strands which depends on the relative direction between the magnetic field, the field sweep rate, and the transport current. Mutual inductances between strands are introduced, allowing the use of the model for nonstationary problems. Time constants can be calculated for both the coupling currents in the strands and for the local and global dissipatio

Super Coupling Currents in Rutherford Type of Cables due to Longitudinal Non-homogeneities of dB/dt

In this paper it is shown that nonhomogeneities in the field sweep rate dB/dt along the length of a Rutherford cable provoke a nonhomogeneous current distribution during a field sweep. This process can be described by means of super coupling currents (SCCs) flowing through the strands over lengths far larger than the cable pitch. These SCCs can be characterised by a characteristic length, a characteristic time, and a propagation velocity. The dependence of these three parameters on the strand resistance and the contact resistance between strands is illustrated. Two longitudinal nonhomogeneities in dB/dt are considered which are present in accelerator magnets. Firstly, an increase in dB/dt from 0 to a certain value simulating that part of the cable where the cable enters the magnet field. Secondly, a longitudinal decrease in dB/dt which occurs mainly in the heads of the magnet. It is shown that in accelerator magnets a nonhomogeneous current distribution induced by the field sweep can not be avoided. However, it seems to be very difficult to estimate the amplitude of the effec

Measurement of jet spectra with charged particles in Pb-Pb collisions at sNN\sqrt{s_{NN}}=2.76 TeV with the ALICE detector

We report a measurement of transverse momentum spectra of jets detected with the ALICE detector in Pb-Pb collisions at \sNN=2.76 TeV. Jets are reconstructed from charged particles using the anti-\kt jet algorithm. The transverse momentum of tracks is measured down to 150 MeV/$c$ which gives access to the low \pt fragments of the jet. The background from soft particle production is determined for each event and subtracted. The remaining influence of underlying event fluctuations is quantified by embedding different probes into heavy-ion data. The reconstructed transverse momentum spectrum is corrected for background fluctuations by unfolding. We observe a strong suppression in central events of inclusive jets reconstructed with radii of 0.2 and 0.3. The fragmentation bias on jets introduced by requiring a high \pt leading particle which rejects jets with a soft fragmentation pattern is equivalent for central and peripheral events.Comment: Quark Matter 2012 proceeding

Comparison of radiative energy loss models in a hot QCD medium

The suppression of high $p_{T}$ hadron production in heavy ion collisions is thought to be due to energy loss by gluon radiation off hard partons in a QCD medium. Existing models of QCD radiative energy loss in a color-charged medium give estimates of the coupling strength of the parton to the medium which differ by a factor of $5$. We will present a side-by-side comparison of two different formalisms to calculate the energy loss of light quarks and gluons: the multiple soft scattering approximation (ASW-MS) and the opacity expansion formalism (ASW-SH and WHDG-rad). A common time-temperature profile is used to characterize the medium. The results are compared to the single hadron suppression $R_{AA}$ at RHIC energies. In addition the influcence of homogeneous and non-homogeneous distribution of scattering centers is discussed. We find that using an equivalent brick overestimates the energy loss for long parton trajectories.Comment: Proceedings Hard Probes 2010, October 10-15, Eilat (Israel

Furnace and rapid thermal crystallization of amorphous GexSi1-x and Si for thin film transistors

The crystallization behavior of polycrystalline silicon (Si) and germanium-silicon alloys (GexSi1−x) from SiH4 and GeH4, where x is in the range of 0-0.32, has been investigated for thin film transistor (TFT) applications. Furnace anneals as well as rapid thermal anneal (RTA) and combinations of these two techniques have been used to crystallize amorphously deposited thin (≤100 nm) films. The effects of time and temperature for the furnace anneals and time, temperature and pulse rate for the RTA have been investigated. Smooth Si and GexSi1−x layers with a surface roughness ≤0.6 nm have been obtained using an initial Si layer for the GexSi1−x material, since GexSi1−x shows a nucleation problem on oxide surfaces which influences the resulting surface roughness and grain size. For TFT applications the optimal film properties cannot be obtained with a single crystallization anneal. Conventional furnace crystallization results in smooth layers with Si furnace crystallized films exhibiting small grains with many intra-grain defects. An average grain size of approximately 300 nm for Ge0.25Si0.75 and slightly larger grains for Ge0.32Si0.68 with less defects is obtained at lower temperature. RTA results for Si and GexSi1−x in fine grained material with lower defect density

Towards a Theory of Constrained Relativism: Comparing and Combining the Work of Pierre Bourdieu, Mary Douglas and Michael Thompson, and Alan Fiske

In this article, I seek to compare Pierre Bourdieu\'s theory of practice, the cultural theory developed by Mary Douglas and Michael Thompson, and the relational models theory pioneered by Alan Fiske, and attempt to sketch how these theories could possibly be combined. I argue that the three theories are among the most interesting conceptual enterprises in the social sciences of the last few decades, as they all represent –quite similar– syntheses of long-standing social-science dualisms, such as objectivism vs. subjectivism, social structure vs. free will, functionalism vs. social conflict, etc. Besides these commonalities, I spell out the relative strengths and weaknesses of each of these approaches. This allows me to conclude by considering whether, and how, it might be possible to synthesise these syntheses by picking the most interesting features of the three theories, and avoiding their less appealing ones.[No keywords]

On the design of a reliability circuit simulator

This paper describes the outcome of a study into the feasibility of a reliability circuit simulator for ICs in general and the critical parameters involved in particular. The necessary conditions are formulated that have to be fulfilled before any construction of the reliability simulator is meaningful or can be done at all. It has been found that failure mechanisms in the wear-out regime meet these conditions. Next, a general approach is given to make a simulator. This approach is actually derived from circuit simulator activities on hot carrier degradation and electromigration, respectively. Finally, the different groups of parameters are defined

Dielectric breakdown I: A review of oxide breakdown

This paper gives an overview of the dielectric breakdown in thin oxide layers on silicon. First test methods are discussed, followed by their application to the estimation of the oxide lifetime. The main part of the paper is devoted to the physical background of the intrinsic breakdown. Finally, defect-related or extrinsic breakdown is discussed