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Selective area doping via ion implantation is crucial to the implementation of most modern devices and the provision of reasonable device design latitude for optimization. Herein, we report highly effective silicon ion implant activation in GaN via Symmetrical Multicycle Rapid Thermal Annealing (SMRTA) at peak temperatures of 1450 to 1530 ?, producing a mobility of up to 137 cm(2)/Vs at 300K with a 57% activation efficiency for a 300 nm thick 1 x 10(19) cm(-3) box implant profile. Doping activation efficiency and mobility improved alongside peak annealing temperature, while the deleterious degradation of the as-grown material electrical properties was only evident at the highest temperatures. This demonstrates efficient dopant activation while simultaneously maintaining low levels of unintentional doping and thus a high blocking voltage potential of the drift layers for high-voltage, high-power devices. Furthermore, efficient activation with high mobility has been achieved with GaN on sapphire, which is known for having relatively high defect densities but also for offering significant commercial potential due to the availability of cheap, large-area, and robust substrates for devices.

In this work, Gallium Nitride Zirconium oxide metal oxide semiconductor capacitors were exposed to a 40MeV proton beam and a 15MeV Argon heavy ion beam of radiation. Characterization of each device was done using an Agilent B1500A, switch matrix, custom-printed circuit board while using a LabVIEW program to analyze the Capacitance-Voltage (C-V), Capacitance-Frequency (C-F), and Current-Voltage (I-V) measurement prior to and post exposure. Each reticle's C-V measurement and its hysteresis was then compared pre- and post-exposure for effects. Testing concluded with a time-dependent dielectric breakdown analysis. Results show that radiation exposure shifts the capacitance of the device and affects the hysteresis in its C-V measurement. Initial time-dependent dielectric breakdown data shows that devices exposed to certain fluences of radiation will extend the time it takes before oxide breakdown.

Beaches that receive more sediment than can be removed by storm erosion will not recede as the sea level rises from future global warming. This research examines the interplay between sediment supply and the frequency and magnitude of storms within the historical record at Bengello Beach, Moruya, New South Wales. During a series of large storms in May-June 1974, Bengello Beach lost approximately 50% of its sand volume and evidence of this erosion is preserved by a 40+ year beach profile campaign that recorded subsequent sediment accumulation. This historical beach-profile history can be contextualised with the barrier’s stratigraphic record captured by the progradation in the past 7,000 years allowing inferences to be made of larger scale changes. The three main objectives of this study are: 1) Examine the links between river flooding, coastal storms and beach changes during large storm events 2) Determine if the Moruya River is delivering sediment to the beach and 3) Analyse the frequency and magnitude of river flooding, coastal storms and beach changes from the historical record and beyond. This methodological approach will focus on analysing pre-existing datasets including: a 40+ year beach profile dataset, a 34- and 46-year wave buoy dataset from Batemans Bay and Port Kembla, peak discharge from the Moruya River and estuarine hydrodynamic models. While it is common to observe intense rain and river flooding in association with coastal storms, preliminary results from the analyses indicate that no strong correlation exist between the occurrence of high river discharge and high significant wave height. However, estuarine hydrodynamic models indicate that sediment reaching the river mouth during floods appears to coincide with increased coastal accretion. Furthermore, within the wave rider buoy records, differences in the quantity, peak significant wave height, duration and period of moderate to extreme storms were noticed on the seasonal scale in addition to an in

Beaches that receive more sediment than can be removed by storm erosion will not recede as the sea level rises from future global warming. This research examines the interplay between sediment supply and the frequency and magnitude of storms within the historical record at Bengello Beach, Moruya, New South Wales. During a series of large storms in May-June 1974, Bengello Beach lost approximately 50% of its sand volume and evidence of this erosion is preserved by a 40+ year beach profile campaign that recorded subsequent sediment accumulation. This historical beach-profile history can be contextualised with the barrier’s stratigraphic record captured by the progradation in the past 7,000 years allowing inferences to be made of larger scale changes. The three main objectives of this study are: 1) Examine the links between river flooding, coastal storms and beach changes during large storm events 2) Determine if the Moruya River is delivering sediment to the beach and 3) Analyse the frequency and magnitude of river flooding, coastal storms and beach changes from the historical record and beyond. This methodological approach will focus on analysing pre-existing datasets including: a 40+ year beach profile dataset, a 34- and 46-year wave buoy dataset from Batemans Bay and Port Kembla, peak discharge from the Moruya River and estuarine hydrodynamic models. While it is common to observe intense rain and river flooding in association with coastal storms, preliminary results from the analyses indicate that no strong correlation exist between the occurrence of high river discharge and high significant wave height. However, estuarine hydrodynamic models indicate that sediment reaching the river mouth during floods appears to coincide with increased coastal accretion. Furthermore, within the wave rider buoy records, differences in the quantity, peak significant wave height, duration and period of moderate to extreme storms were noticed on the seasonal scale in addition to an in

Beaches that receive more sediment than can be removed by storm erosion will not recede as the sea level rises from future global warming. This research examines the interplay between sediment supply and the frequency and magnitude of storms within the historical record at Bengello Beach, Moruya, New South Wales. During a series of large storms in May-June 1974, Bengello Beach lost approximately 50% of its sand volume and evidence of this erosion is preserved by a 40+ year beach profile campaign that recorded subsequent sediment accumulation. This historical beach-profile history can be contextualised with the barrier’s stratigraphic record captured by the progradation in the past 7,000 years allowing inferences to be made of larger scale changes. The three main objectives of this study are: 1) Examine the links between river flooding, coastal storms and beach changes during large storm events 2) Determine if the Moruya River is delivering sediment to the beach and 3) Analyse the frequency and magnitude of river flooding, coastal storms and beach changes from the historical record and beyond. This methodological approach will focus on analysing pre-existing datasets including: a 40+ year beach profile dataset, a 34- and 46-year wave buoy dataset from Batemans Bay and Port Kembla, peak discharge from the Moruya River and estuarine hydrodynamic models. While it is common to observe intense rain and river flooding in association with coastal storms, preliminary results from the analyses indicate that no strong correlation exist between the occurrence of high river discharge and high significant wave height. However, estuarine hydrodynamic models indicate that sediment reaching the river mouth during floods appears to coincide with increased coastal accretion. Furthermore, within the wave rider buoy records, differences in the quantity, peak significant wave height, duration and period of moderate to extreme storms were noticed on the seasonal scale in addition to an in

Background: The cortisol awakening response (CAR) has been used as a biomarker of stress response in a multitude of psychological investigations. While a myriad of biochemical responses have been proposed to monitor responses to exercise training, the use of CAR within the exercise and sports sciences is currently limited and is a potentially underutilized variable. Therefore, the purpose of this review was to collate studies that incorporate both exercise and CAR, in an effort to better understand (a) whether CAR is a useful marker for monitoring exercise stress and (b) how CAR may be most appropriately used in future research.Methods: A systematic review of the literature was conducted, following PRISMA guidelines. Searches were conducted using PubMed, SportDISCUS, Scopus, and PsychInfo databases, using search terms related toCAR and exercise and physical activity.Results: 10,292 articles were identified in the initial search, with 32 studies included in the final analysis. No studies investigated the effects of laboratory-controlled exercise on CAR. Variable effects were observed, possibly due to inconsistencies in study design, methodology, population, and CAR analysis. The available literature suggests a threshold of exercise may be required to alter the HPA axis and affect CAR. Moreover, CAR may represent a combination of previous exercise load and upcoming stress, making current interpretation of field-based observational research challenging.Conclusions: More research is needed to fully elucidate the influence of exercise on CAR and address a number of gaps in the literature, including controlling exercise load, consistent sample collection, and CAR calculation and analysis.

Purpose: Cortisol (C) and testosterone (T) are impacted significantly by prolonged endurance exercise with inverse responses. Increases in C are witnessed concurrently with decrements in T, possibly impacting recovery. This study was conducted to assess the dynamics of C and free T (fT) concentration and recovery time following an exhaustive endurance exercise session (EES).Methods: 12 endurance-trained males (X ± SD: VO2max 66.3±4.8 ml/kg/min, age 22.8 ± 3.1 years, body fat 11.0 ± 1.4 %, training 7.1 ± 3.2 years) completed a treadmill EES at ventilatory threshold (74.7 ± 4.6 % of VO2max; 96.9 ± 10.8 min). Basal blood C and fT were collected at baseline: -48, -24 h, and immediately before (0 h) the EES as well as immediately (+0 h), +24 h, +48 h, and +72 h after the EES. Blood glucose (G) was measured to confirm no undue influence on C. Statistically data were analyzed with repeated measures ANOVA (LSD post hoc).Results: C (nmol/L) increased significantly from -48 h (321 ± 59) to +0 h (701 ± 178) (p Conclusions: EES recovery may require 48 h for C and 72 h for fT to return to baseline values. Furthermore, C and fT were only correlated immediately post-exercise. Future research should perform more frequent measurements throughout time course.

This study investigated the validity of salivary cortisol responses to reflect blood cortisol responses relative to the magnitude of change observed over time in the hormone. Male subjects (n=25) conducted four experimental sessions (ES) where blood (B) and saliva (S) were obtained before (PS) and after (PoS) a 30 min resting control, 40%, 60%, and 80% of maximal aerobic capacity (VO2max) exercise ES. B and S specimens were analyzed by standard biochemical procedures. Hormonal concentrations changes were assessed by using absolute delta (DA) values (PoS – PS) and percent change (PC) calculations ((PoS-PS)/PS x 100) for each B and S specimen. Subsequent DA and PC values were correlated (Pearson) for each B-S specimen pairing (n=100; n=25 x 4 ES). Results indicate the magnitude of change (PoS vs. PS) in S cortisol is more valid and strongly associated (p<0.001) with corresponding B changes (the “gold standard”) when expressing the data as delta values using absolute hormonal concentrations as compared to percent change expression.

Cancer treatment is associated with adverse changes in strength, body composition, physical function, and quality of life. Exercise training reduces cancer incidence and mortality rates and may offset some of the treatment-related effects. To determine the independent effects of strength training (ST) on the effects of cancer treatment, an initial search was performed in March and then updated in November 2015. Additional articles were identified by scanning references from relevant articles. Studies using traditional ST on strength, body composition, aerobic capacity, functional assessments, and psychosocial parameters were included. Excluded studies had no objective strength measurement or combined ST with additional exercise. Mean and standard deviations from 39 studies across seven cancer types were extracted for main outcomes. ST-induced change scores with 95 % confidence intervals were calculated and were evaluated with paired t tests, where appropriate. Twenty to fifty percent improvements in maximal strength were observed, indicating that the ST programs were effective. Physical function was also enhanced (7–38 %), although gains were less consistent. Body composition and psychosocial changes were rare, with only a few changes in selected cancer types. As such, ST appears to promote benefits that may be specific to cancer types. Strength was the only consistent outcome that improved in all cancer survivors. However, these gains in strength are still of tremendous importance, given its impact on functionality and quality of life. Several practical considerations for exercise testing, training, and data reporting are presented for consideration to improve the overall depth of the field.

PAPER Trapping phenomena in AlGaN and InAlN barrier HEMTs with different geometries S Martin-Horcajo1, A Wang1, A Bosca1, M F Romero1, M J Tadjer1,2, A D Koehler2, T J Anderson2 and F Calle1 Published 11 February 2015 • © 2015 IOP Publishing Ltd Semiconductor Science and Technology, Volume 30, Number 3 Article PDF Figures References Citations Metrics 350 Total downloads Cited by 1 articles Export citation and abstract BibTeX RIS Turn on MathJax Share this article Article information Abstract Trapping effects were evaluated by means of pulsed measurements under different quiescent biases for GaN/AlGaN/GaN and GaN/InAlN/GaN. It was found that devices with an AlGaN barrier underwent an increase in the on-resistance, and a drain current and transconductance reduction without measurable threshold voltage change, suggesting the location of the traps in the gate-drain access region. In contrast, devices with an InAlN barrier showed a transconductance and a decrease in drain associated with a significant positive shift of threshold voltage, indicating that the traps were likely located under the gate region; as well as an on-resistance degradation probably associated with the presence of surface traps in the gate-drain access region. Furthermore, measurements of drain current transients at different ambient temperatures revealed that the activation energy of electron traps was 0.43 eV and 0.38 eV for AlGaN and InAlN barrier devices, respectively. Experimental and simulation results demonstrated the influence of device geometry on the observed trapping effects, since devices with larger gate lengths and gate-to-drain distance values exhibited less noticeable charge trapping effects.

Proton-induced damage in AlGaN/GaN HEMTs was investigated using energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM), and simulated using a Monte Carlo technique. The results were correlated to electrical degradation using Hall measurements. It was determined by EDS that the interface between GaN and AlGaN in the irradiated HEMT was broadened by 2.2nm, as estimated by the width of the Al EDS signal compared to the as-grown interface. The simulation results show a similar Al broadening effect. The extent of interfacial roughening was examined using high resolution TEM. At a 2MeV proton fluence of 6 × 10{sup 14} H{sup +}/cm{sup 2}, the electrical effects associated with the Al broadening and surface roughening include a degradation of the ON-resistance and a decrease in the electron mobility and 2DEG sheet carrier density by 28.9% and 12.1%, respectively.

PAPER Trapping phenomena in AlGaN and InAlN barrier HEMTs with different geometries S Martin-Horcajo1, A Wang1, A Bosca1, M F Romero1, M J Tadjer1,2, A D Koehler2, T J Anderson2 and F Calle1 Published 11 February 2015 • © 2015 IOP Publishing Ltd Semiconductor Science and Technology, Volume 30, Number 3 Article PDF Figures References Citations Metrics 350 Total downloads Cited by 1 articles Export citation and abstract BibTeX RIS Turn on MathJax Share this article Article information Abstract Trapping effects were evaluated by means of pulsed measurements under different quiescent biases for GaN/AlGaN/GaN and GaN/InAlN/GaN. It was found that devices with an AlGaN barrier underwent an increase in the on-resistance, and a drain current and transconductance reduction without measurable threshold voltage change, suggesting the location of the traps in the gate-drain access region. In contrast, devices with an InAlN barrier showed a transconductance and a decrease in drain associated with a significant positive shift of threshold voltage, indicating that the traps were likely located under the gate region; as well as an on-resistance degradation probably associated with the presence of surface traps in the gate-drain access region. Furthermore, measurements of drain current transients at different ambient temperatures revealed that the activation energy of electron traps was 0.43 eV and 0.38 eV for AlGaN and InAlN barrier devices, respectively. Experimental and simulation results demonstrated the influence of device geometry on the observed trapping effects, since devices with larger gate lengths and gate-to-drain distance values exhibited less noticeable charge trapping effects.

CIVINS (Civilian Institutions) Thesis document, Ship operational profiles are a valuable tool for ship designers and engineers when analyzing potential designs and ship system selections. The most common is the speed-time profile, normally depicted as a histogram showing the percent of time spent at each speed. Many shortcomings exist in the current Arleigh Burke (DDG 51)-class operational profiles. The current speed-time profile is out of date, based on another ship class, and does not depict the profile in one-knot increments. Additional profile data, such as how the engineering plant is operated and a mission profile, do not exist. A thorough analysis of recent DDG-51 operations was conducted and new and improved profiles were developed. These profiles indicate the ships tend to operate at slower speeds than was previously predicted with 46% of the time spent at 8 knots and below as compared to the previous profiles with 28% at the same speeds. Additionally, profiles were developed to show the amount of time spent in each engineering plant line-up (69% train shaft, 24% split plant, 7% full power) and the time spent in different mission types (69% operations, 27% transit, 4% restricted maneuvering doctrine). A detailed statistical analysis was then conducted to better understand the data used in profile development and to create a region of likely speed-time profiles rather than just a point solution that is presented in the composite speed-time profile. This was accomplished through studying the underlying distributions of the data as well as the variance., http://archive.org/details/operationalprofi1094540211, US Navy (USN) author.

Epitaxial GaN films were grown by metal organic chemical vapor deposition (MOCVD) on functionalized epitaxial graphene (EG) using a thin (approxmately 11 nm) conformal AlN nucleation layer. Raman measurements show a graphene 2D peak at 2719 cm(exp -1) after GaN growth. X-ray diffraction analysis reveals [0001]-oriented hexagonal GaN with (0002) peak rocking curve full width at the half maximum (FWHM) of 544 arcsec. The FWHM values are similar to reported values for GaN grown by MOCVD on sapphire. The GaN layer has a strong room-temperature photoluminescence band edge emission. Successful demonstration of GaN growth on EG opens up the possibility of III nitride/graphene heterostructure-based electronic devices and promises improved performance., Published in Applied Physics Express v6 article 061003; published online 7 Jun 2013. The original document contains color images.

Detailed spectrometry and optical spectroscopy studies carried out on GaN crystals grown in solution detect and identify Mg as the dominant shallow acceptor. Selective etching of crystals with higher Mg levels than that of the donor concentration background indicates that Mg acceptors incorporate preferentially in the N-polar face. Electrical transport measurements verified an efficient incorporation and activation of the Mg acceptors. These results suggest that this growth method has the potential to produce p-type doped epitaxial layers or p-type substrates characterized by high hole concentration and low defect density., Published in Applied Physics Express, v6 article ID 111001, 11 Oct 2013.

Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013., "June 2013." Cataloged from PDF version of thesis., Includes bibliographical references (p. 60-62)., Ship operational profiles are a valuable tool for ship designers and engineers when analyzing potential designs and ship system selections. The most common is the speed-time profile, normally depicted as a histogram showing the percent of time spent at each speed. Many shortcomings exist in the current Arleigh Burke (DDG 51)-class operational profiles. The current speed-time profile is out of date, based on another ship class, and does not depict the profile in one-knot increments. Additional profile data, such as how the engineering plant is operated and a mission profile, do not exist. A thorough analysis of recent DDG 51 operations was conducted and new and improved profiles were developed. These profiles indicate the ships tend to operate at slower speeds than was previously predicted with 46% of the time spent at 8 knots and below as compared to the previous profile with 28% for the same speeds. Additionally, profiles were developed to show the amount of time spent in each engineering plant line-up (69% trail shaft, 24% split plant, 7% full power) and the time spent in different mission types (69% operations, 27% transit, 4% restricted maneuvering doctrine). A detailed statistical analysis was then conducted to better understand the data used in profile development and to create a region of likely speed-time profiles rather than just a point solution that is presented in the composite speed-time profile. This was accomplished through studying the underlying distributions of the data as well as the variance., by Travis J. Anderson., Nav.E.and S.M.

Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013., "June 2013." Cataloged from PDF version of thesis., Includes bibliographical references (p. 60-62)., Ship operational profiles are a valuable tool for ship designers and engineers when analyzing potential designs and ship system selections. The most common is the speed-time profile, normally depicted as a histogram showing the percent of time spent at each speed. Many shortcomings exist in the current Arleigh Burke (DDG 51)-class operational profiles. The current speed-time profile is out of date, based on another ship class, and does not depict the profile in one-knot increments. Additional profile data, such as how the engineering plant is operated and a mission profile, do not exist. A thorough analysis of recent DDG 51 operations was conducted and new and improved profiles were developed. These profiles indicate the ships tend to operate at slower speeds than was previously predicted with 46% of the time spent at 8 knots and below as compared to the previous profile with 28% for the same speeds. Additionally, profiles were developed to show the amount of time spent in each engineering plant line-up (69% trail shaft, 24% split plant, 7% full power) and the time spent in different mission types (69% operations, 27% transit, 4% restricted maneuvering doctrine). A detailed statistical analysis was then conducted to better understand the data used in profile development and to create a region of likely speed-time profiles rather than just a point solution that is presented in the composite speed-time profile. This was accomplished through studying the underlying distributions of the data as well as the variance., by Travis J. Anderson., Nav.E.and S.M.

Vertical diodes of epitaxial graphene on n 4H-SiC were investigated. The graphene Raman spectraexhibited a higher intensity in the G-line than the 2D-line, indicative of a few-layer graphene film.Rectifying properties improved at low temperatures as the reverse leakage decreased over six ordersof magnitude without freeze-out in either material. Carrier concentration of 10 16 cm 3in the SiCremained stable down to 15 K, while accumulation charge decreased and depletion width increasedin forward bias. The low barrier height of 0.08 eV and absence of recombination-induced emissionindicated majority carrier field emission as the dominant conduction mechanism.

There has been significant research in the study of in-plane charge-carrier transport in graphene in order to understand and exploit its unique electrical properties; however, the vertical graphene–semiconductor system also presents opportunities for unique devices. In this letter, we investigate the epitaxial graphene/p-type 4H-SiC system to better understand this vertical heterojunction. The I–V behavior does not demonstrate thermionic emission properties that are indicative of a Schottky barrier but rather demonstrates characteristics of a semiconductor heterojunction. This is confirmed by the fitting of the temperature-dependent I–V curves to classical heterojunction equations and the observation of band-edge electroluminescence in SiC.

There has been significant research in the study of in-plane charge-carrier transport in graphene in order to understand and exploit its unique electrical properties; however, the vertical graphene–semiconductor system also presents opportunities for unique devices. In this letter, we investigate the epitaxial graphene/p-type 4H-SiC system to better understand this vertical heterojunction. The I–V behavior does not demonstrate thermionic emission properties that are indicative of a Schottky barrier but rather demonstrates characteristics of a semiconductor heterojunction. This is confirmed by the fitting of the temperature-dependent I–V curves to classical heterojunction equations and the observation of band-edge electroluminescence in SiC.

Vertical diodes of epitaxial graphene on n 4H-SiC were investigated. The graphene Raman spectraexhibited a higher intensity in the G-line than the 2D-line, indicative of a few-layer graphene film.Rectifying properties improved at low temperatures as the reverse leakage decreased over six ordersof magnitude without freeze-out in either material. Carrier concentration of 10 16 cm 3in the SiCremained stable down to 15 K, while accumulation charge decreased and depletion width increasedin forward bias. The low barrier height of 0.08 eV and absence of recombination-induced emissionindicated majority carrier field emission as the dominant conduction mechanism.

As an emerging optical material, graphene s ultrafast dynamics are often probed using pulsed lasers yet the region in which optical damage takes place is largely uncharted. Here, femtosecond laser pulses induced localized damage in single-layer graphene on sapphire. Raman spatial mapping, SEM, and AFM microscopy quantified the damage. The resulting size of the damaged area has a linear correlation with the optical fluence. These results demonstrate local modification of sp2-carbon bonding structures with optical pulse fluences as low as 14 mJ/cm2, an order-of-magnitude lower than measured and theoretical ablation thresholds., Pub. in Applied Physics Letters, v99 p211909-1/211909-3, 2011.

Relacionado con línea de investigación del GDS del ISOM ver http://www.isom.upm.es/dsemiconductores.php

As an emerging optical material, graphene’s ultrafast dynamics are often probed using pulsed lasers yet the region in which optical damage takes place is largely uncharted. Here, femtosecond laser pulses induced localized damage in single-layer graphene on sapphire. Raman spatial mapping, SEM, and AFM microscopy quantified the damage. The resulting size of the damaged area has a linear correlation with the optical fluence. These results demonstrate local modification of sp2-carbon bonding structures with optical pulse fluences as low as 14 mJ/cm2, an order-of-magnitude lower than measured and theoretical ablation thresholds.

As an emerging optical material, graphene’s ultrafast dynamics are often probed using pulsed lasers yet the region in which optical damage takes place is largely uncharted. Here, femtosecond laser pulses induced localized damage in single-layer graphene on sapphire. Raman spatial mapping, SEM, and AFM microscopy quantified the damage. The resulting size of the damaged area has a linear correlation with the optical fluence. These results demonstrate local modification of sp2-carbon bonding structures with optical pulse fluences as low as 14 mJ/cm2, an order-of-magnitude lower than measured and theoretical ablation thresholds.

Relacionado con línea de investigación del GDS del ISOM ver http://www.isom.upm.es/dsemiconductores.php

A threshold reverse bias of 21 V was observed leading to a sharp increase in the gate current of AlGaN/GaN high electron mobility transistors biased at low source-drain voltage (5 V). The gate current increases by one to two orders of magnitude at this bias, corresponding to an electric field strength around 1.8 MV cm 1. The gate current increased by roughly five orders of magnitude after step-stressing the gate bias from 10 to 42 V in 1 V increments for 1 min at each bias. The drain current was also decreased by 20% after this step-stress cycle. The photoluminescence and electroluminescence intensity from the semiconductor is decreased along the periphery of the gate region after stressing and transmission electron microscopy shows a thin native oxide layer under the gate and this disappears as the gate metal reacts with the underlying AlGaN., Published in Journal of Vacuum Science Technology B, v28 n5 p1044-1047, September/October 2010.

We examine oxygen-isotope exchanges in a nanometer-size oxide molecule in water and, separately, both its rates of dissociation and molecular products. This molecule, the decaniobate ion ([H(x),Nb(10)O(28)]((6-x)-)), is at the same size scale as geochemically interesting features on minerals, such as surface polymers and kink sites on growth steps, although it is structurally quite dissimilar. Unlike mineral surface structures, however, we have complete confidence in the aqueous structure of this molecule and it yields a clear spectroscopic signature as it reacts. We thus can follow proton-enhanced isotope exchanges and base-induced dissociation in unprecedented detail and clarity. The results are surprising and require new thinking about geochemical reactions at the molecular scale. For example, base-induced dissociation of the molecule, which is unprotonated, causes rates of oxygen-isotope exchanges of all structural oxygens to accelerate dramatically. Similarly, protonation of the molecule causes sets of oxygens to react, although protonation is limited. In general, all reactions are via concerted motions of many atoms and the reactivities vary as though the entire structure was responding to changes in solution composition. The site reactivities could not be inferred from the stable structure of the decaniobate molecule because so much of the structure is involved in each exchange event. Thus, computational models must be structurally faithful to an extraordinary degree, and inherently dynamic, or they will miss the essential chemistry.

In this work, Gallium Nitride Zirconium oxide metal oxide semiconductor capacitors were exposed to a 40MeV proton beam and a 15MeV Argon heavy ion beam of radiation. Characterization of each device was done using an Agilent B1500A, switch matrix, custom-printed circuit board while using a LabVIEW program to analyze the Capacitance-Voltage (C-V), Capacitance-Frequency (C-F), and Current-Voltage (I-V) measurement prior to and post exposure. Each reticle's C-V measurement and its hysteresis was then compared pre- and post-exposure for effects. Testing concluded with a time-dependent dielectric breakdown analysis. Results show that radiation exposure shifts the capacitance of the device and affects the hysteresis in its C-V measurement. Initial time-dependent dielectric breakdown data shows that devices exposed to certain fluences of radiation will extend the time it takes before oxide breakdown., Lieutenant, United States Navy, Approved for public release. distribution is unlimited