Time evolution of dislocation formation in ion implanted silicon

Annealing of crystal damage from ion implantation may result in dislocation formation. Here we study the nucleation, growth, and annihilation of such dislocations during rapid thermal anneals of Si, Ge, As, and In implanted Si. The dislocation formation process is observed for single or multiple damage profiles, as well as in amorphous-crystal transition regions. Dislocations initially nucleate in all these cases, even if they eventually annihilate during further annealing. It is also shown that for C implants in Si not only do dislocations not remain after annealing, but they do not even nucleate

Designing the Dynamics of Coupled Oscillators

By designing coupling to control populations of oscillators, we can control their synchonisation behaviour. Oscillators (e.g. neurons) can be coupled on different levels. The most basic level is through links between pairs of oscillators. However, using graphs with only pairwise links is not necessarily a satisfactory approximation of reality as nonpairwise interactions can be found in many dynamical systems including social networks and the human brain. Even though the effects of these nonpairwise interactions have been observed, described and modeled in a wide range of oscillatory systems, controlling nonpairwise interactions in arbitrary populations of oscillators has remained a relatively unexplored area. In this thesis we generalise synchronisation engineering to control nonpairwise interactions in arbitrary systems. We designed a nonlinear time-delayed coupling that can be used to match the phase reduction of a system of oscillators to a target phase model. The contribution of this thesis is allowing for nonpairwise interactions in the target phase model. We used an optimisation proceidure to find coupling parameters to match a nonpairwise target phase model that has the collective behaviour we aim to introduce to the system We found that we need one additional filter to find the parameter sets that match the bifurcation of both in-phase and splay configuration in to the nonpairwise target phase model

Improvement of device characteristics by multiple step implants or introducing a C gettering layer

Ion implantation is used for realization of the collector in vertical bipolar transistors in a BiCMOS process. Secondary defects, remaining after annealing the implant damage, can give rise to an increased leakage current and to collector-emitter shorts. Two methods are proposed to avoid dislocation formation. First, by using multiple step implants, and second, by application of a carbon gettering layer. Experimental results show that these schemes can lower leakage currents, and moreover dramatically increase device yield. However, the carbon profile needs a further optimization with respect to the quality of the collector-substrate junction

Ecotypic variation in phenotypic plasticity: Evolution and ecological consequense of thermal reaction norms

Ellers, J. [Promotor

Dislocation formation in silicon implanted at different temperatures

The formation of pre-amorphization damage, i.e. dislocations formed by the agglomeration of silicon interstitials, requires a minimum amount of implant damage. The amount of damage can be altered by changing the implant temperature or current density, which can influence dislocation formation. We studied this using cross-sectional transmission electron microscopy for boron and indium implants at kiloelectronvolt and megaelectronvolt energies respectively. Dislocation formation for boron implants, where only simple cascade densities are generated, does not depend on implant temperature or current density. For 1 MeV indium implants, where the implant damage consists mainly of amorphous zones, an increase in critical dose for dislocation formation by a factor of approximately 3 is observed if the implant temperature is raised. This is attributed to the interaction of point defects with the amorphous zones during the elevated temperature implant. Implants of 150 keV indium at room temperature result in complete amorphization before the critical amount of crystal damage is reached. Here, end-of-range loops (EOR-loops) from after annealing. Increasing the implant temperature suppresses amorphization, and pre-amorphization damage is observed if a critical amount of crystal damage has been generated. EOR-loop formation results from the agglomeration of silicon interstitials from the amorphous-crystalline transition region. If the number of interstitials in this region is lowered by carrying out the implant at low temperature, EOR-loop formation can be suppressed. This is shown by comparing amorphizing germanium implants done at room and liquid nitrogen temperatures

Openness and Commitment: A conversation between a theological debate and the practice of intentional interreligious encounter in Malaysia

Interculturele Theologi

A hydrological model to estimate pollution from combined sewer overflows at the regional scale: Application to Europe

Study region Combined Sewer Overflows (CSO) of 671 Functional Urban Areas (FUAs) throughout the European Union + UK (EU28), representing almost half of the EU28 population. Study focus CSO loads can be quantified at the local scale through measurements, or with calibrated hydrological models. However, they are difficult to quantify at a large scale (e.g. regional or national), due to a lack of data, and the models used at local scale cannot be applied in the absence of knowledge of the combined sewer (CS) network. This paper presents a 6-parameter lumped hydrological model to simulate a CS network and its overflows, using population and rainfall data of 671 EU28 FUAs. New hydrological insights for the region When properly calibrated, the model can predict the CSO hydrographs as well as aggregated CSO descriptors of a catchment with known impervious surface area connected to a CS with a reasonable reliability. When model calibration is not possible, using default values of the parameters enables a first approximation estimate of CSOs, accurate within one order of magnitude, which can be used to support scenario analysis for regional and continental CSO management. At the EU28 scale, the estimated total CSO volume is 5.7·10$^3$ Mm$^3$/y, with a dry weather flow content in CSOs of 460 Mm$^3$/y (assuming a dry weather flow of 200 l/population equivalent (PE)/day including sanitary discharges, industrial discharge and infiltration). A collection of case studies on CSOs is also provided

Costs and benefits of combined sewer overflow management strategies at the European scale

Combined sewer overflows (CSOs) may represent a significant source of pollution, but they are difficult to quantify at a large scale (e.g. regional or national), due to a lack of accessible data. In the present study, we use a large scale, 6-parameter, lumped hydrological model to perform a screening level assessment of different CSO management scenarios for the European Union and United Kingdom, considering prevention and treatment strategies. For each scenario we quantify the potential reduction of CSO volumes and duration, and estimate costs and benefits. A comparison of scenarios shows that treating CSOs before discharge in the receiving water body (e.g. by constructed wetlands) is more cost-effective than preventing CSOs. Among prevention strategies, urban greening has a benefit/cost ratio one order of magnitude higher than grey solutions, due to the several additional benefits it entails. We also estimate that real time control may bring on average a CSO volume reduction of just above 20%. In general, the design of appropriate CSO management strategies requires consideration of context-specific conditions, and is best made in the context of an integrated urban water management plan taking into account factors such as other ongoing initiatives in urban greening, the possibility to disconnect impervious surfaces from combined drainage systems, and the availability of space for grey or nature-based solutions