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Analytical models for total dose ionization effects in MOS devices

Bogdan, Carolyn W.

MOS devices are susceptible to damage by ionizing radiation due to charge buildup in gate, field and SOI buried oxides. Under positive bias holes created in the gate oxide will transport to the Si / SiO{sub 2} interface creating oxide-trapped charge. As a result of hole transport and trapping, hydrogen is liberated in the oxide which can create interface-trapped charge. The trapped charge will affect the threshold voltage and degrade the channel mobility. Neutralization of oxidetrapped charge by electron tunneling from the silicon and by thermal emission can take place over long periods of time. Neutralization of interface-trapped charge is not observed at room temperature. Analytical models are developed that account for the principal effects of total dose in MOS devices under different gate bias. The intent is to obtain closed-form solutions that can be used in circuit simulation. Expressions are derived for the aging effects of very low dose rate radiation over long time periods.

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TYPE SAND Report YEAR 2008
DOIOSTI

The Sandia MEMS passive shock sensor : FY07 maturation activities

Mitchell, John A.; Baker, Michael S.; Blecke, Jill; Clemens, Rebecca C.; Epp, David S.; Houston, Jack E.; Walraven, Jeremy; Wittwer, Jonathan W.

This report describes activities conducted in FY07 to mature the MEMS passive shock sensor. The first chapter of the report provides motivation and background on activities that are described in detail in later chapters. The second chapter discusses concepts that are important for integrating the MEMS passive shock sensor into a system. Following these two introductory chapters, the report details modeling and design efforts, packaging, failure analysis and testing and validation. At the end of FY07, the MEMS passive shock sensor was at TRL 4.

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TYPE SAND Report YEAR 2008
DOIOSTI

Qualitative Evaluation of the Accuracy of Maps for Release of Hazardous Materials

Darby, John L.

The LinguisticBelief© software tool developed by Sandia National Laboratories was applied to provide a qualitative evaluation of the accuracy of various maps that provide information on releases of hazardous material, especially radionuclides. The methodology, "Uncertainty for Qualitative Assessments," includes uncertainty in the evaluation. The software tool uses the mathematics of fuzzy sets, approximate reasoning, and the belief/ plausibility measure of uncertainty. SNL worked cooperatively with the Remote Sensing Laboratory (RSL) and the National Atmospheric Release Advisory Center (NARAC) at Lawrence Livermore National Laboratory (LLNL) to develop models for three types of maps for use in this study. SNL and RSL developed the maps for "Accuracy Plot for Area" and "Aerial Monitoring System (AMS) Product Confidence". SNL and LLNL developed the "LLNL Model". For each of the three maps, experts from RSL and LLNL created a model in the LinguisticBelief software. This report documents the three models and provides evaluations of maps associated with the models, using example data. Future applications will involve applying the models to actual graphs to provide a qualitative evaluation of the accuracy of the maps, including uncertainty, for use by decision makers. A "Quality Thermometer" technique was developed to rank-order the quality of a set of maps of a given type. A technique for pooling expert option from different experts was provided using the PoolEvidence© software.

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TYPE SAND Report YEAR 2008
DOIOSTI

Enhanced Photocurrent Efficiency of a Carbon Nanotube Embedded in a Photonic Structure

Wong, Bryan M.

One of the most rapidly-growing areas in nanoscience is the ability to artificially manipulate optical and electrical properties at the nanoscale. In particular, nanomaterials such as single-wall carbon nanotubes offer enhanced methods for converting infrared light to electrical energy due to their unique one-dimensional electronic properties. However, in order for this energy conversion to occur, a realistic nanotube device would require high-intensity light to be confined on a nanometer scale. This arises from the fact that the diameter of a single nanotube is on the order of a nanometer, and infrared light from an external source must be tightly focused on the narrow nanotube for efficient energy conversion. To address this problem, I calculate the theoretical photocurrent of a nanotube p-n junction illuminated by a highly-efficient photonic structure. These results demonstrate the utility of using a photonic structure to couple large-scale infrared sources with carbon nanotubes while still retaining all the unique optoelectronic properties found at the nanoscale.

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TYPE SAND Report YEAR 2008
DOIOSTI

Determination of late-time Gamma-Ray (60Co) sensitivity of single diffusion Lot 2N2222A transistors

Depriest, Kendall R.; Kajder, Karen C.

Sandia National Laboratories (SNL) has embarked on a program to develop a methodology to use damage relations techniques (alternative experimental facilities, modeling, and simulation) to understand the time-dependent effects in transistors (and integrated circuits) caused by neutron irradiations in the Sandia Pulse Reactor-III (SPR-III) facility. The development of these damage equivalence techniques is necessary since SPR-III was shutdown in late 2006. As part of this effort, the late time {gamma}-ray sensitivity of a single diffusion lot of 2N2222A transistors has been characterized using one of the {sup 60}Co irradiation cells at the SNL Gamma Irradiation Facility (GIF). This report summarizes the results of the experiments performed at the GIF.

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TYPE SAND Report YEAR 2008
DOIOSTI

Navy fuel cell demonstration project

Akhil, Abbas A.; Black, Billy D.

This is the final report on a field evaluation by the Department of the Navy of twenty 5-kW PEM fuel cells carried out during 2004 and 2005 at five Navy sites located in New York, California, and Hawaii. The key objective of the effort was to obtain an engineering assessment of their military applications. Particular issues of interest were fuel cell cost, performance, reliability, and the readiness of commercial fuel cells for use as a standalone (grid-independent) power option. Two corollary objectives of the demonstration were to promote technological advances and to improve fuel performance and reliability. From a cost perspective, the capital cost of PEM fuel cells at this stage of their development is high compared to other power generation technologies. Sandia National Laboratories technical recommendation to the Navy is to remain involved in evaluating successive generations of this technology, particularly in locations with greater environmental extremes, and it encourages their increased use by the Navy.

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TYPE SAND Report YEAR 2008
DOIOSTI
Results 77101–77200 of 99,299
Results 77101–77200 of 99,299