463 research outputs found
Temperature dependent carrier lifetime studies of Mo in crystalline silicon
The capture cross sections of both electronsÏn and holes Ïp were determined for interstitialmolybdenum in crystalline silicon over the temperature range of â110 to 150â°C. Carrier lifetimemeasurements were performed on molybdenum-contaminated silicon using a temperature controlled photoconductance instrument. Injection dependent lifetime spectroscopy was applied at each temperature to calculate Ïp and Ïn. This analysis involved a novel approach that independently determined the capture cross sections at each temperature assuming a known defect density and thermal velocity. Since the energy state is in the lower half of the bandgap, the determination of Ïp is unaffected by the defect energy at all temperatures, and Ïp is found to decrease with temperature in a fashion consistent with excitonic Auger capture. At temperatures below 0â°C, the determination of Ïn is also unaffected by the defect energy due to the suppression of thermal emission, and Ïn decreases with temperature as well. It is shown that a projection of Ïn to higher temperature suggests the defect has an energy of 0.375 eV above the valance band edge of silicon.D.M. likes to thank the Australian Research Council for
fellowship and G.C. likes to thank âCrystalClear Integrated
Projectâ Contract No. SES6-CT_2003-502583 funded by
the European Commission
The impact of varying statutory arrangements on spatial data sharing and access in regional NRM bodies
Spatial information plays an important role in many social, environmental and economic decisions and increasingly acknowledged as a national resource essential for wider societal and environmental benefits. Natural Resource Management is one area where spatial information can be used for improved planning and decision making processes. In Australia, state government organisations are the custodians of spatial information necessary for natural resource management and regional NRM bodies are responsible to regional delivery of NRM activities. The access and sharing of spatial information between government agencies and regional NRM bodies is therefore as an important issue for improving natural resource management outcomes. The aim of this paper is to evaluate the current status of spatial information access, sharing and use with varying statutory arrangements and its impacts on spatial data infrastructure (SDI) development in catchment management sector in Australia. Further, it critically examined whether any trends and significant variations exist due to different institutional arrangements (statutory versus non-statutory) or not. A survey method was used to collect primary data from 56 regional natural resource management (NRM) bodies responsible for catchment management in Australia. Descriptive statistics method was used to show the similarities and differences between statutory and non-statutory arrangements. The key factors which influence sharing and access to spatial information are also explored. The results show the current statutory and administrative arrangements and regional focus for natural resource management is reasonable from a spatial information management perspective and provides an opportunity for building SDI at the catchment scale. However, effective institutional arrangements should align catchment SDI development activities with sub-national and national SDI development activities to address catchment management issues. We found minor differences in spatial information access, use and sharing due to varying institutional environment (statutory versus non-statutory). The non-statutory group appears to be more flexible and self-sufficient whilst statutory regional NRM bodies may lack flexibility in their spatial information management practices. We found spatial information access, use and sharing has significant impacts on spatial data infrastructure development in catchment management sector in Australia
Estimating the burden of minor ailment consultations in general practices and emergency departments through retrospective review of routine data in North East Scotland
Minor ailment attendances in general practices and emergency departments (EDs) place significant burden on health care resources
Temperature dependent carrier lifetime studies on Ti-doped multicrystalline silicon
Carrier lifetimemeasurements were performed on deliberately Ti-doped multicrystalline silicon wafers using a temperature controlled photoconductance device. The dominant recombination center was found to be the double-donor level associated with interstitial titanium. The interstitial Ti concentrations in multicrystalline silicon wafers were determined by measuring the ShockleyâReadâHall time constant for holes and using the known values of the thermal velocity and capture cross section for holes of the double-donor level at different temperatures. The measured values of the Ti concentration were then used to determine the electron capture cross section of the double-donor level over the temperature range of 140â270â°C via the measured values of the ShockleyâReadâHall time constant for electrons and the known thermal velocity. Multiphonon emission was found to be the most likely capture mechanism for this temperature range for electron capture into the double-donor level of Ti in silicon. The effective segregation coefficient for Ti was estimated by fitting Scheilâs equation to the measured values of the Ti concentrations and their respective vertical positions in the ingot. If all Ti were present as the interstitial double-donor, a lower limit of 1.8Ă10â»â¶ can be ascribed to the segregation coefficient, which is very close to the equilibrium value.This work was funded by an Australian Research
Council Linkage Grant between the Australian National
University, SierraTherm Production Furnaces, and
SunPower Corporation. D.H.M. is supported by an Australian
Research Council fellowship
Generalized procedure to determine the dependence of steady-state photoconductance lifetime on the occupation of multiple defects
We present a procedure to determine the dependence of photoconductance lifetime on the occupation of multiple defects. The procedure requires numerical iteration, making it more cumbersome than the analytical equations available for single-defect and simplified two-defect cases, but enabling the following features: (i) it accounts for the defect concentration when calculating the equilibrium carrier concentrations, (ii) it permits recombination through any number of defects, (iii) it calculates the occupation fraction of all defects at any injection, and (iv) it promotes a good understanding of the role of defect occupation in photoconductance measurements. The utility of the numerical procedure is demonstrated on an experimental sample containing multiple defects. The dependence of the sampleâs photoconductance on carrier concentration and temperature can be qualitatively described by the generalized procedure but not by either analytical model. The example also demonstrates that the influence of defect occupation on photoconductance lifetime measurements is mitigated at elevated temperaturesâa conclusion of particular worth to the study of multicrystalline silicon.This work was
funded by an Australian Research Council Linkage Grant
between the Australian National University, SierraTherm Production Furnaces, and SunPower Corporation. D.M. is
supported by an Australian Research Council fellowship
Current evidence of MTX efficacy in childhood chronic uveitis: a systematic review and meta-analysis
Maize in Nepal: Production Systems, Constraints, and Priorities for Research
Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,
Complex magnetism of lanthanide intermetallics unravelled
We explain a profound complexity of magnetic interactions of some
technologically relevant gadolinium intermetallics using an ab-initio
electronic structure theory which includes disordered local moments and strong
-electron correlations. The theory correctly finds GdZn and GdCd to be
simple ferromagnets and predicts a remarkably large increase of Curie
temperature with pressure of +1.5 K kbar for GdCd confirmed by our
experimental measurements of +1.6 K kbar. Moreover we find the origin of
a ferromagnetic-antiferromagnetic competition in GdMg manifested by
non-collinear, canted magnetic order at low temperatures. Replacing 35\% of the
Mg atoms with Zn removes this transition in excellent agreement with
longstanding experimental data.Comment: 11 pages, 4 figure
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