383 research outputs found

    Temperature dependent carrier lifetime studies of Mo in crystalline silicon

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    The capture cross sections of both electronsσn and holes σp were determined for interstitialmolybdenum in crystalline silicon over the temperature range of −110 to 150 °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 σp and σn. 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 σp is unaffected by the defect energy at all temperatures, and σp is found to decrease with temperature in a fashion consistent with excitonic Auger capture. At temperatures below 0 °C, the determination of σn is also unaffected by the defect energy due to the suppression of thermal emission, and σn decreases with temperature as well. It is shown that a projection of σn 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 “CrystalClear Integrated Project” 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

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    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

    Generalized procedure to determine the dependence of steady-state photoconductance lifetime on the occupation of multiple defects

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    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 sample’s 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 temperatures—a 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

    Complex magnetism of lanthanide intermetallics unravelled

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    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 ff-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 kbar1^{-1} for GdCd confirmed by our experimental measurements of +1.6 K kbar1^{-1}. 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

    Assessing Cadastre 2034 to Develop a Federated Cadastral System in New South Wales Australia: Mixed Methods Research Approach

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    Cadastre 2034 is a National Strategy developed by the Intergovernmental Committee on Surveying and Mapping (ICSM) for cadastral reform and innovation for Australia and one of the goals is to develop a federated cadastral system. It states to define governance and administration on a federal level by unifying the existing systems with uniform standards, policies, guidelines and legislation and to allow further work towards a global cadastre. The aim of this research paper is to explore the behaviours and attitudes of New South Wales (NSW) cadastre towards a federated cadastral system assessing the best practice of federated cadastre global cases that may be applied locally in Australia. Mixed Methods Research (MMR) methodology was used, involving both quantitative and qualitative research to understand, identify and frame the cadastral data to determine and analyse the key issues and factors in implementing a federated cadastral system in New South Wales (NSW). A literature review, a questionnaire survey and interviews were used to collect the quantitative and qualitative data. A sequential MMR design framework was used a questionnaire survey followed by interviews. The questionnaire was sent out to 215 industry and government participants and resulted 71 completed surveys. Semi-structured interviews were conducted with 9 participants. The linking of quantitative and qualitative data occurred at the design-level, where results from the first phase were used to build the second phase of research design. It was explored that strong historical foundations, regressive reaction of governments and institutions, and a lack of understanding of the significance of cadastral reform were the key hindering factors to develop a federated cadastral system in NSW. The resulting analysis could be contributed to a better implementation of a federated cadastral system in NSW benefitting private, and public institutions
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