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1. Can Neptune's Distant Mean-Motion Resonances Constrain Undiscovered Planets in the Solar System? Lessons from a Case Study of the 9:1

Author

Porter, Matthew W., Gerdes, David W., Napier, Kevin J., Lin, Hsing Wen, and Adams, Fred C.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Recent observational surveys of the outer Solar System provide evidence that Neptune's distant $n$:1 mean-motion resonances may harbor relatively large reservoirs of trans-Neptunian objects (TNOs). In particular, the discovery of two securely classified 9:1 resonators, 2015 KE$_{172}$ and 2007 TC$_{434}$, by the Outer Solar System Origins Survey is consistent with a population of order $10^4$ such objects in the 9:1 resonance with absolute magnitude $H_r < 8.66$. This work investigates whether the long-term stability of such populations in Neptune's $n$:1 resonances can be used to constrain the existence of distant $5-10M_{\oplus}$ planets orbiting at hundreds of AU. The existence of such a planet has been proposed to explain a reported clustering in the orbits of highly eccentric "extreme" trans-Neptunian objects (eTNOs), although this hypothesis remains controversial. We engage in a focused computational case-study of the 9:1 resonance, generating synthetic populations and integrating them for 1 Gyr in the presence of 81 different test planets with various masses, perihelion distances, eccentricities, and inclinations. While none of the tested planets are incompatible with the existence of 9:1 resonators, our integrations shed light on the character of the interaction between such planets and nearby $n$:1 resonances, and we use this knowledge to construct a simple, heuristic method for determining whether or not a given planet could destabilize a given resonant population. We apply this method to the currently estimated properties of Planet 9, and find that a large primordial population in the 15:1 resonance (or beyond), if discovered in the future, could potentially constrain the existence of this planet., Comment: 20 pages, 16 figures

Published
2024

2. The DECam Ecliptic Exploration Project (DEEP): V. The Absolute Magnitude Distribution of the Cold Classical Kuiper Belt

Author

Napier, Kevin J., Lin, Hsing-Wen, Gerdes, David W., Adams, Fred C., Simpson, Anna M., Porter, Matthew W., Weber, Katherine G., Markwardt, Larissa, Gowman, Gabriel, Smotherman, Hayden, Bernardinelli, Pedro H., Jurić, Mario, Connolly, Andrew J., Kalmbach, J. Bryce, Portillo, Stephen K. N., Trilling, David E., Strauss, Ryder, Oldroyd, William J., Trujillo, Chadwick A., Chandler, Colin Orion, Holman, Matthew J., Schlichting, Hilke E., McNeill, Andrew, and Collaboration, the DEEP

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The DECam Ecliptic Exploration Project (DEEP) is a deep survey of the trans-Neptunian solar system being carried out on the 4-meter Blanco telescope at Cerro Tololo Inter-American Observatory in Chile using the Dark Energy Camera (DECam). By using a shift-and-stack technique to achieve a mean limiting magnitude of $r \sim 26.2$, DEEP achieves an unprecedented combination of survey area and depth, enabling quantitative leaps forward in our understanding of the Kuiper Belt populations. This work reports results from an analysis of twenty 3 sq.\ deg.\ DECam fields along the invariable plane. We characterize the efficiency and false-positive rates for our moving-object detection pipeline, and use this information to construct a Bayesian signal probability for each detected source. This procedure allows us to treat all of our Kuiper Belt Object (KBO) detections statistically, simultaneously accounting for efficiency and false positives. We detect approximately 2300 candidate sources with KBO-like motion at S/N $>6.5$. We use a subset of these objects to compute the luminosity function of the Kuiper Belt as a whole, as well as the Cold Classical (CC) population. We also investigate the absolute magnitude ($H$) distribution of the CCs, and find consistency with both an exponentially tapered power-law, which is predicted by streaming instability models of planetesimal formation, and a rolling power law. Finally, we provide an updated mass estimate for the Cold Classical Kuiper Belt of $M_{CC}(H_r < 12) = 0.0017^{+0.0010}_{-0.0004} M_{\oplus}$, assuming albedo $p = 0.15$ and density $\rho = 1$ g cm$^{-3}$., Comment: Accepted by PSJ

Published
2023

3. Resilient Control of Platooning Networked Robotic Systems via Dynamic Watermarking

Author

Porter, Matthew, Joshi, Arnav, Dey, Sidhartha, Wu, Qirui, Hespanhol, Pedro, Aswani, Anil, Johnson-Roberson, Matthew, and Vasudevan, Ram

Subjects
Mathematics - Optimization and Control, Electrical Engineering and Systems Science - Systems and Control
Abstract

Networked robotic systems, such as connected vehicle platoons, can improve the safety and efficiency of transportation networks by allowing for high-speed coordination. To enable such coordination, these systems rely on networked communications. This can make them susceptible to cyber attacks. Though security methods such as encryption or specially designed network topologies can increase the difficulty of successfully executing such an attack, these techniques are unable to guarantee secure communication against an attacker. More troublingly, these security methods are unable to ensure that individual agents are able to detect attacks that alter the content of specific messages. To ensure resilient behavior under such attacks, this paper formulates a networked linear time-varying version of dynamic watermarking in which each agent generates and adds a private excitation to the input of its corresponding robotic subsystem. This paper demonstrates that such a method can enable each agent in a networked robotic system to detect cyber attacks. By altering measurements sent between vehicles, this paper illustrates that an attacker can create unstable behavior within a platoon. By utilizing the dynamic watermarking method proposed in this paper, the attack is detected, allowing the vehicles in the platoon to gracefully degrade to a non-communicative control strategy that maintains safety across a variety of scenarios., Comment: 19 pages, 7 figures

Published
2021

5. Detecting Deception Attacks on Autonomous Vehicles via Linear Time-Varying Dynamic Watermarking

Author

Porter, Matthew, Dey, Sidhartha, Joshi, Arnav, Hespanhol, Pedro, Aswani, Anil, Johnson-Roberson, Matthew, and Vasudevan, Ram

Subjects
Mathematics - Optimization and Control, Electrical Engineering and Systems Science - Systems and Control
Abstract

Cyber-physical systems (CPS) such as autonomous vehicles rely on both on-board sensors and external communications to estimate their state. Unfortunately, these communications render the system vulnerable to cyber-attacks. While many attack detection methods have begun to address these concerns, they are limited to linear time-invariant (LTI) systems. Though LTI system models provide accurate approximations for CPS such as autonomous vehicles at constant speed and turning radii, they are inaccurate for more complex motions such as lane changes, turns, and changes in velocity. Since these more complex motions are more suitably described by linear time-varying (LTV) system models rather than LTI models, Dynamic Watermarking, which adds a private excitation to the input signal to validate measurements, has recently been extended to LTV systems. However, this extension does not allow for LTV systems that require several steps before the effect of a given control input can be seen in the measurement signal. Additionally, there is no consideration for the time-varying effects of auto-correlation. Furthermore, a proof of concept was only provided using simulations of a simplified model. This paper relaxes the requirement for inputs to be visible in a single step and constructs an auto-correlation normalizing factor to remove the effects of auto-correlation. In addition, Dynamic Watermarking is applied to a high-fidelity vehicle model in carsim and a 1/10 scale autonomous rover to further reinforce the proof of concept for realistic systems. In each case, the vehicle follows a predefined path with time-varying velocity and turning radii. A replay attack, which replays previously recorded measurements, is shown to be detectable using LTV Dynamic Watermarking in a quick and repeatable manner., Comment: 8 pages, 4 figures. arXiv admin note: text overlap with arXiv:1909.08111

Published
2020

8. High-temperature ceramic matrix composites prepared via microwave energy enhanced chemical vapour infiltration

Author

Porter, Matthew Thomas

Subjects
TN Mining engineering. Metallurgy, TP Chemical technology, TS Manufactures
Abstract

SiC fibre reinforced SiC composites must be >90% dense in order to offer a superior structural material alternative to current systems used in aerospace engines. To achieve this the use of microwave energy enhanced chemical vapour infiltration (MCVI) has been investigated as a possible faster and more energy efficient manufacturing route. Key processing parameters were identified and their effects on the rate of deposition of SiC and the composite's microstructure were assessed using a suite of characterisation techniques. The rate of SiC deposition had an Arrhenius relationship with the temperature and the use of microwaves is thought to have also lowered the activation energy of the decomposition reaction. The fundamental benefit of this advanced processing method was the inverse thermal gradient produced by using microwave energy. This was studied both experimentally and via finite-difference time-domain modelling (FDTD). The latter showed a direct correlation between susceptor size and microwave absorption. A SiC slurry calendaring impregnation route was also developed to fill macro porosity in the SiC fibre preform. A number of slurries were characterised to find a suitable slurry composition that reduced the total volume of porosity in the preform to further reduce CVI processing time.

Published
2020

9. Detecting Generalized Replay Attacks via Time-Varying Dynamic Watermarking

Author

Porter, Matthew, Hespanhol, Pedro, Aswani, Anil, Johnson-Roberson, Matthew, and Vasudevan, Ram

Subjects
Mathematics - Optimization and Control, Electrical Engineering and Systems Science - Systems and Control
Abstract

Cyber-physical systems (CPS) often rely on external communication for supervisory control or sensing. Unfortunately, these communications render the system vulnerable to cyber-attacks. Attacks that alter messages, such as replay attacks that record measurement signals and then play them back to the system, can cause devastating effects. Dynamic Watermarking methods, which inject a private excitation into control inputs to secure resulting measurement signals, have begun addressing the challenges of detecting these attacks, but have been restricted to linear time invariant (LTI) systems. Though LTI models are sufficient for some applications, other CPS, such as autonomous vehicles, require more complex models. This paper develops a linear time-varying (LTV) extension to previous Dynamic Watermarking methods by designing a matrix normalization factor to accommodate the temporal changes in the system. Implementable tests are provided with considerations for real-world systems. The proposed method is then shown to be able to detect generalized replay attacks both in theory and in simulation using a LTV vehicle model., Comment: 16 pages, 2 figures

Published
2019

10. Sensor Switching Control Under Attacks Detectable by Finite Sample Dynamic Watermarking Tests

Author

Hespanhol, Pedro, Porter, Matthew, Vasudevan, Ram, and Aswani, Anil

Subjects
Mathematics - Optimization and Control, Electrical Engineering and Systems Science - Systems and Control
Abstract

Control system security is enhanced by the ability to detect malicious attacks on sensor measurements. Dynamic watermarking can detect such attacks on linear time-invariant (LTI) systems. However, existing theory focuses on attack detection and not on the use of watermarking in conjunction with attack mitigation strategies. In this paper, we study the problem of switching between two sets of sensors: One set of sensors has high accuracy but is vulnerable to attack, while the second set of sensors has low accuracy but cannot be attacked. The problem is to design a sensor switching strategy based on attack detection by dynamic watermarking. This requires new theory because existing results are not adequate to control or bound the behavior of sensor switching strategies that use finite data. To overcome this, we develop new finite sample hypothesis tests for dynamic watermarking in the case of bounded disturbances, using the modern theory of concentration of measure for random matrices. Our resulting switching strategy is validated with a simulation analysis in an autonomous driving setting, which demonstrates the strong performance of our proposed policy., Comment: 13 pages, 3 figures

Published
2019

11. Simulation and Real-World Evaluation of Attack Detection Schemes

Author

Porter, Matthew, Joshi, Arnav, Hespanhol, Pedro, Aswani, Anil, Johnson-Roberson, Matthew, and Vasudevan, Ram

Subjects
Computer Science - Systems and Control
Abstract

A variety of anomaly detection schemes have been proposed to detect malicious attacks to Cyber-Physical Systems. Among these schemes, Dynamic Watermarking methods have been proven highly effective at detecting a wide range of attacks. Unfortunately, in contrast to other anomaly detectors, no method has been presented to design a Dynamic Watermarking detector to achieve a user-specified false alarm rate, or subsequently evaluate the capabilities of an attacker under such a selection. This paper describes methods to measure the capability of an attacker, to numerically approximate this metric, and to design a Dynamic Watermarking detector that can achieve a user-specified rate of false alarms. The performance of the Dynamic Watermarking detector is compared to three classical anomaly detectors in simulation and on a real-world platform. These experiments illustrate that the attack capability under the Dynamic Watermarking detector is comparable to those of classic anomaly detectors. Importantly, these experiments also make clear that the Dynamic Watermarking detector is consistently able to detect attacks that the other class of detectors are unable to identify.

Published
2018

13. Statistical Watermarking for Networked Control Systems

Author

Hespanhol, Pedro, Porter, Matthew, Vasudevan, Ram, and Aswani, Anil

Subjects
Mathematics - Optimization and Control, Computer Science - Systems and Control
Abstract

Watermarking can detect sensor attacks in control systems by injecting a private signal into the control, whereby attacks are identified by checking the statistics of the sensor measurements and private signal. However, past approaches assume full state measurements or a centralized controller, which is not found in networked LTI systems with subcontrollers. Since generally the entire system is neither controllable nor observable by a single subcontroller, communication of sensor measurements is required to ensure closed-loop stability. The possibility of attacking the communication channel has not been explicitly considered by previous watermarking schemes, and requires a new design. In this paper, we derive a statistical watermarking test that can detect both sensor and communication attacks. A unique (compared to the non-networked case) aspect of the implementing this test is the state-feedback controller must be designed so that the closed-loop system is controllable by each sub-controller, and we provide two approaches to design such a controller using Heymann's lemma and a multi-input generalization of Heymann's lemma. The usefulness of our approach is demonstrated with a simulation of detecting attacks in a platoon of autonomous vehicles. Our test allows each vehicle to independently detect attacks on both the communication channel between vehicles and on the sensor measurements.

Published
2017

14. Dynamic Watermarking for General LTI Systems

Author

Hespanhol, Pedro, Porter, Matthew, Vasudevan, Ram, and Aswani, Anil

Subjects
Mathematics - Optimization and Control, Computer Science - Systems and Control
Abstract

Detecting attacks in control systems is an important aspect of designing secure and resilient control systems. Recently, a dynamic watermarking approach was proposed for detecting malicious sensor attacks for SISO LTI systems with partial state observations and MIMO LTI systems with a full rank input matrix and full state observations; however, these previous approaches cannot be applied to general LTI systems that are MIMO and have partial state observations. This paper designs a dynamic watermarking approach for detecting malicious sensor attacks for general LTI systems, and we provide a new set of asymptotic and statistical tests. We prove these tests can detect attacks that follow a specified attack model (more general than replay attacks), and we also show that these tests simplify to existing tests when the system is SISO or has full rank input matrix and full state observations. The benefit of our approach is demonstrated with a simulation analysis of detecting sensor attacks in autonomous vehicles. Our approach can distinguish between sensor attacks and wind disturbance (through an internal model principle framework), whereas improperly designed tests cannot distinguish between sensor attacks and wind disturbance.

Published
2017

15. Correction for Gaulke et al., “Intestinal Epithelial Barrier Disruption through Altered Mucosal MicroRNA Expression in Human Immunodeficiency Virus and Simian Immunodeficiency Virus Infections”

Author

Gaulke, Christopher A, Porter, Matthew, Han, Yan-Hong, Sankaran-Walters, Sumathi, Grishina, Irina, George, Michael D, Dang, Angeline T, Ding, Shou-Wei, Jiang, Guochun, Korf, Ian, and Dandekar, Satya

Subjects
Medical Microbiology, Biomedical and Clinical Sciences, Immunology, Biological Sciences, Agricultural and Veterinary Sciences, Medical and Health Sciences, Virology, Agricultural, veterinary and food sciences, Biological sciences, Biomedical and clinical sciences
Abstract

MicroRNA sequences are now publicly available. Page 6270, last paragraph in Materials and Methods, line 1: "Microarray data accession number" should read "Accession numbers." Page 6270, last paragraph in Materials and Methods, line 4: The following sentence should be added. "MicroRNA sequencing data have been deposited in the NCBI BioProject database under accession no. PRJNA429684 and in the NCBI Sequence Read Archive under accession no. SRP128960.".

Published
2018

16. The collaborative effect of scientific meetings: A study of the International Milk Genomics Consortium.

Author

Kwok, Eric, Porter, Matthew, Pasin, Gonca, German, J, Korf, Ian, and Lemay, Danielle

Subjects
Animals, Authorship, Congresses as Topic, Cooperative Behavior, Genomics, Journal Impact Factor, Milk
Abstract

Collaboration among scientists has a major influence on scientific progress. Such collaboration often results from scientific meetings, where scientists gather to present and discuss their research and to meet potential collaborators. However, most scientific meetings have inherent biases, such as the availability of research funding or the selection bias of professional societies that make it difficult to study the effect of the meeting per se on scientific productivity. To evaluate the effects of scientific meetings on collaboration and progress independent of these biases, we conducted a study of the annual symposia held by the International Milk Genomics Consortium (IMGC) over a 12-year period. In our study, we conducted permutation testing to analyze the effectiveness of the IMGC in facilitating collaboration and productivity in a community of milk scientists who were meeting attendees relative to non-attendees. Using the number of co-authorships on published papers as a measure of collaboration, our analysis revealed that scientists who attended the symposium were associated with more collaboration than were scientists who did not attend. Furthermore, we evaluated the scientific progress of consortium attendees by analyzing publication rate and article impact. We found that IMGC attendees, in addition to being more collaborative, were also more productive and influential than were non-attendees who published in the same field. The results of our study suggest that the annual symposium encouraged interactions among disparate scientists and increased research productivity, exemplifying the positive effect of scientific meetings on both collaboration and progress.

Published
2018

17. Evaluation of the Safety of Uninterrupted Warfarin Anticoagulation With Tranexamic Acid in Total Joint Arthroplasty.

Author

Johnston, Michael G., Porter, Matthew A., Eppich, Kade E., Gray, Celeste G., and Scott, David F.

Subjects
WARFARIN, TRANEXAMIC acid, ARTHROPLASTY, ANTICOAGULANTS, BLOOD transfusion, COMORBIDITY
Abstract

Background: The continuation of long-term warfarin therapy is gaining acceptance in minor surgeries but maintaining therapeutic international normalized ratio (INR) values among patients during major orthopedic procedures raises concern. While bridging therapy with low-molecular-weight heparin is currently recommended for patients receiving anticoagulation, few studies have evaluated the safety of continuing warfarin during total joint arthroplasty. This study evaluated the safety and efficacy of continuous warfarin anticoagulation through total joint arthroplasty with and without prophylactic tranexamic acid (TXA). Materials and Methods: We conducted a retrospective, matched-pair analysis of two experimental groups of patients who underwent primary total hip arthroplasty or total knee arthroplasty performed by a single surgeon. Our first experimental group, warfarin plus TXA (warfarin+TXA), consisted of 21 patients who underwent arthroplasty while receiving therapeutic anticoagulation with warfarin (INR, 2.0–3.0) and who received prophylactic TXA. Our second experimental group, warfarin without TXA (warfarin-TXA), consisted of 40 patients who underwent arthroplasty while receiving therapeutic anticoagulation with warfarin (INR, 2.0–3.0) without prophylactic TXA. Results: The percent change in hemoglobin value after surgery, red blood cells transfused, surgical site infections, bleeding complications, and thrombotic complications were similar between both experimental and control groups. When comparing the historical group with the warfarin+TXA group, the addition of TXA resulted in a statistical decrease in mean red blood cells transfused and estimated blood loss, with no statistically significant increase in complications. Conclusion: Many factors must be considered when choosing perioperative thromboembolic prophylaxis for arthroplasty candidates with medical comorbidities requiring long-term anticoagulation. This study presents data indicating that it could be safe and effective to continue therapeutic warfarin while using prophylactic TXA. [Orthopedics. 2024;47(4):211–216.] [ABSTRACT FROM AUTHOR]

Published
2024
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18. The DECam Ecliptic Exploration Project (DEEP). V. The Absolute Magnitude Distribution of the Cold Classical Kuiper Belt

Author

Napier, Kevin J., primary, Lin 林, Hsing Wen 省 文, additional, Gerdes, David W., additional, Adams, Fred C., additional, Simpson, Anna M., additional, Porter, Matthew W., additional, Weber, Katherine G., additional, Markwardt, Larissa, additional, Gowman, Gabriel, additional, Smotherman, Hayden, additional, Bernardinelli, Pedro H., additional, Jurić, Mario, additional, Connolly, Andrew J., additional, Kalmbach, J. Bryce, additional, Portillo, Stephen K. N., additional, Trilling, David E., additional, Strauss, Ryder, additional, Oldroyd, William J., additional, Trujillo, Chadwick A., additional, Chandler, Colin Orion, additional, Holman, Matthew J., additional, Schlichting, Hilke E., additional, and McNeill, Andrew, additional

Published
2024
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20. The Radio numbers of all graphs of order $n$ and diameter $n-2$

Author

Benson, Katherine, Porter, Matthew, and Tomova, Maggy

Subjects
Mathematics - Combinatorics, 05C78 (05C15, 05C38)
Abstract

A radio labeling of a connected graph $G$ is a function $c:V(G) \to \mathbb Z_+$ such that for every two distinct vertices $u$ and $v$ of $G$ $$\text{distance}(u,v)+|c(u)-c(v)|\geq 1+ \text{diameter}(G).$$ The radio number of a graph $G$ is the smallest integer $M$ for which there exists a labeling $c$ with $c(v)\leq M$ for all $v\in V(G)$. The radio number of graphs of order $n$ and diameter $n-1$, i.e., paths, was determined in \cite{paths}. Here we determine the radio numbers of all graphs of order $n$ and diameter $n-2$., Comment: 21 pages, 10 figures

Published
2012

21. Intestinal Epithelial Barrier Disruption through Altered Mucosal MicroRNA Expression in Human Immunodeficiency Virus and Simian Immunodeficiency Virus Infections

Author

Gaulke, Christopher A, Porter, Matthew, Han, Yan-Hong, Sankaran-Walters, Sumathi, Grishina, Irina, George, Michael D, Dang, Angeline T, Ding, Shou-Wei, Jiang, Guochun, Korf, Ian, and Dandekar, Satya

Subjects
Medical Microbiology, Biomedical and Clinical Sciences, Immunology, Biotechnology, Genetics, HIV/AIDS, Infectious Diseases, Digestive Diseases, 2.1 Biological and endogenous factors, Aetiology, Oral and gastrointestinal, Infection, Adult, Animals, Base Sequence, CD4-Positive T-Lymphocytes, Computational Biology, Densitometry, Flow Cytometry, HIV, Humans, Intestinal Mucosa, Laser Capture Microdissection, Lentivirus Infections, Macaca mulatta, Male, MicroRNAs, Microarray Analysis, Middle Aged, Molecular Sequence Data, Real-Time Polymerase Chain Reaction, Sequence Analysis, RNA, Simian Immunodeficiency Virus, Viral Load, Simian immunodeficiency virus, Biological Sciences, Agricultural and Veterinary Sciences, Medical and Health Sciences, Virology, Agricultural, veterinary and food sciences, Biological sciences, Biomedical and clinical sciences
Abstract

UnlabelledEpithelial barrier dysfunction during human immunodeficiency virus (HIV) infection has largely been attributed to the rapid and severe depletion of CD4(+) T cells in the gastrointestinal (GI) tract. Although it is known that changes in mucosal gene expression contribute to intestinal enteropathy, the role of small noncoding RNAs, specifically microRNA (miRNA), has not been investigated. Using the simian immunodeficiency virus (SIV)-infected nonhuman primate model of HIV pathogenesis, we investigated the effect of viral infection on miRNA expression in intestinal mucosa. SIV infection led to a striking decrease in the expression of mucosal miRNA compared to that in uninfected controls. This decrease coincided with an increase in 5'-3'-exoribonuclease 2 protein and alterations in DICER1 and Argonaute 2 expression. Targets of depleted miRNA belonged to molecular pathways involved in epithelial proliferation, differentiation, and immune response. Decreased expression of several miRNA involved in maintaining epithelial homeostasis in the gut was localized to the proliferative crypt region of the intestinal epithelium. Our findings suggest that SIV-induced decreased expression of miRNA involved in epithelial homeostasis, disrupted expression of miRNA biogenesis machinery, and increased expression of XRN2 are involved in the development of epithelial barrier dysfunction and gastroenteropathy.ImportanceMicroRNA (miRNA) regulate the development and function of intestinal epithelial cells, and many viruses disrupt normal host miRNA expression. In this study, we demonstrate that SIV and HIV disrupt expression of miRNA in the small intestine during infection. The depletion of several key miRNA is localized to the proliferative crypt region of the gut epithelium. These miRNA are known to control expression of genes involved in inflammation, cell death, and epithelial maturation. Our data indicate that this disruption might be caused by altered expression of miRNA biogenesis machinery during infection. These findings suggest that the disruption of miRNA in the small intestine likely plays a role in intestinal enteropathy during HIV infection.

Published
2014

24. GAN LIGHT EMISSION CONTROLLED DC-DC CONVERTER

Author

Weatherford, Todd R., Corzine, Keith, UC Santa Cruz, Porter, Matthew A., Electrical and Computer Engineering (ECE), Johnston, Justin D., Weatherford, Todd R., Corzine, Keith, UC Santa Cruz, Porter, Matthew A., Electrical and Computer Engineering (ECE), and Johnston, Justin D.

Abstract

This work demonstrates the very first implementation of electroluminescence from a gallium nitride vertical diode as a feedback mechanism for real-time current control of a power converter. Current estimation via electroluminescence provides a galvanically isolated sensor capability that is not susceptible to electromagnetic interference, which is inherently produced in switch mode power supplies. The light feedback is converted to an electrical signal that is further digitally filtered to construct a 3D current calibration surface. This surface converts duty cycle and light signal intensity into a real-time current estimation utilized as a feedback parameter in a buck converter control system. The accuracy of current estimation is shown to be within 5% of steady-state current over various load conditions. Transient-state response was also demonstrated for step changes in commanded current and voltage within the power converter. Methods of increasing accuracy and reducing current estimation delay time are discussed., Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Published
2023

25. DESIGN AND IMPLEMENTATION OF A DATA ACQUISITION SYSTEM WITH IN-SITU PICOAMMETER FOR AUTOMATED RELIABILITY TESTING

Author

Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), Ramos, Richard A., Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), and Ramos, Richard A.

Abstract

In recent years, the military has been exploring the use of wide bandgap semiconductors (WBGS) such as gallium nitride (GaN) and silicon carbide (SiC) due to their promising material properties, as compared to silicon (Si). Understanding the reliability of these high-performance WBGS devices is paramount to their implementation in military systems. However, it remains to be tested because good-quality reliability data is needed, but it is difficult and expensive to produce. This thesis looks at the design and implementation of a modular reliability testing subsystem in the form of a novel data acquisition system. First, a system was designed to perform automated, in-situ leakage current measurements of up to four devices under test (DUT) with sub-nA resolution. Next, a wide sample of devices consisting of a resistor, two Zener diodes, a power diode, two GaN diodes, and a field effect transistor (FET) were subjected to various voltage sweep and reverse-bias tests that were recorded by the system. Finally, the results of those validation tests were processed and analyzed. The system achieved leakage current resolutions below 100 pA, demonstrating its ability to measure various devices., ONR Arlington, VA, 22217, Captain, United States Marine Corps, Approved for public release. Distribution is unlimited.

Published
2023

26. OPTIMIZATION OF LIGHT EXTRACTION FROM HIGH-VOLTAGE SIC PIN DIODE VIA PACKAGE DESIGN

Author

Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), Martin, John K., II, Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), and Martin, John K., II

Abstract

This work demonstrates improved light extraction from a silicon carbide (SiC) PiN diode via package optimization. Previous research has shown that SiC power devices have low on-state voltage drop while maintaining a large breakdown voltage, making them desirable for high-power systems. SiC produces insufficient amounts of electroluminescence due to being an indirect bandgap semiconductor. Device packaging utilizing ray optics can maximize electroluminescent output. A packaging model is developed using computer aided design (CAD) software that supports light production and high-power operation with associated heat and electric potential constraints. The packaged SiC PiN diode is shown to have a light extraction improvement of 1740%. Methods of device production and follow-on testing are also discussed., Office of Naval Research, Arlington VA 22203, Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Published
2023

27. Control and Prognosis of Power Electronic Devices Using Light

Author

Corzine, Keith, Weatherford, Todd, Porter, Matthew, Corzine, Keith, Weatherford, Todd, and Porter, Matthew

Abstract

An optically-monitored and/or optically-controlled electronic device is described. The device includes at least one of a semiconductor transistor or a semiconductor diode. An optical detector is configured to detect light emitted by the at least one of the semiconductor transistor or the semiconductor diode during operation. A signal processor is configured to communicate with the optical detector to receive information regarding the light detected. The signal processor is further configured to provide information concerning at least one of an electrical current flowing in, a temperature of, or a condition of the at least one of the semiconductor transistor or the semiconductor diode during operation.

Published
2023

28. Implanted Guard Ring Edge Termination With Avalanche Capability for Vertical GaN Devices

Author

Wang, Yifan, Porter, Matthew, Xiao, Ming, Lu, Albert, Yee, Nathan, Kravchenko, Ivan, Srijanto, Bernadeta, Cheng, Kai, Wong, Hiu Yung, and Zhang, Yuhao

Abstract

Edge termination is the key building block in power devices to enable near-ideal, avalanche breakdown voltage (BV). This work presents the design, fabrication, and physics of a GaN guard ring (GR) edge termination formed by selective-area nitrogen implantation through an epitaxial p-GaN layer. The fabrication of this termination only includes a single implantation step that does not require precise control of implant depth, rendering a large process latitude. The selective-area implantation produces p-GaN rings that are separated by the implanted, semi-insulating regions. The number and spacing of the p-type rings are found to determine the BV of the vertical GaN p-n diode. The 16-ring structure enables a BV of 1800 V, being 88% of the theoretical 1-D parallel-plane limit. Avalanche characteristics are observed in devices with a large variety of GR designs. Finally, we present a comprehensive survey on the efficiency, fabrication complexity, real estate, and avalanche capability of various edge termination techniques that have been reported in vertical GaN devices. The high efficiency (among the highest reported in avalanche-capable GaN terminations), simple and robust fabrication process, and uniform avalanche capability make this implanted GR a promising edge termination for high-voltage GaN devices.

Published
2024
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33. A STUDY FOCUSING ON THE EFFECTS OF HTOL STRESS ON THE LUMINESCENCE SPECTRUM OF GAN DIODES TO CHARACTERIZE COMPONENT DEGRADATION

Author

Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), Electrical and Computer Engineering (ECE), Kavanagh, Shawn R., Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), Electrical and Computer Engineering (ECE), and Kavanagh, Shawn R.

Abstract

Wide bandgap (WBG) semiconductor technology allows devices to be operated at higher voltages, currents, temperatures, and frequencies than does conventional silicon-based narrow bandgap semiconductors. These characteristics are advantageous to military applications, such as uses in power converters, weapons, and radar systems. Notably, WBG semiconductors have advantages where cooling and space availability for components are concerns, such as unmanned underwater platforms. The ability to monitor the health and performance of these devices passively and remotely would reduce the man-hours required for preventative maintenance; it would also reduce the needs for invasive troubleshooting and needless component replacement. This thesis demonstrates the abilities to measure and analyze the electroluminescence spectrum of WBG devices using a custom-built high-temperature operating life (HTOL) test setup incorporating the ability to sample light spectroscopy., Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Published
2022

34. Comparison of Clinical Outcomes Following Gel Stent Implantation via Ab-Externo and Ab-Interno Approaches in Patients with Refractory Glaucoma

Author

Gallardo,Mark J, Vincent,Logan R, Porter,Matthew, Gallardo,Mark J, Vincent,Logan R, and Porter,Matthew

Abstract

Mark J Gallardo,1– 3 Logan R Vincent,1 Matthew Porter2 1El Paso Eye Surgeons, El Paso, TX, USA; 2Department of Ophthalmology, Texas Tech University School of Medicine, Lubbock, TX, USA; 3Department of Ophthalmology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX, USACorrespondence: Mark J Gallardo, El Paso Eye Surgeons, 1201 N Mesa St, Ste G, El Paso, TX, 79902, USA, Tel +1 915 542 0279, Email gallardomark@hotmail.comPurpose: To compare clinical outcomes following gel stent implantation via ab externo and ab interno approaches in patients with refractory glaucoma.Patients and Methods: This retrospective study included 203 eyes of 185 patients aged ≥ 45 years who underwent Xen gel stent implantation as a standalone procedure for medically uncontrolled glaucoma (intraocular pressure (IOP) ≥ 18 mmHg) despite maximum tolerable IOP-lowering medications. One hundred and five eyes underwent gel stent implantation via ab interno approach and 98 via ab externo. Patients with prior conjunctival-incisional glaucoma or cataract surgery were also included. Study parameters were reduction in IOP and number of IOP-lowering medications from baseline to 3, 6, 9 and 12 months postoperatively.Results: There were no statistically significant differences in the age, sex, preoperative IOP, number of IOP-lowering medications or cup–disc ratio between the ab interno and ab externo groups at baseline (p > 0.05). At all postoperative time points, mean IOP and percentage reduction from baseline were comparable in both groups (p > 0.05) except at postoperative 6 months when the outcomes were significantly better (p < 0.05) in the ab externo group. The rate of postoperative procedures (5-Fluorouracil injections and bleb needling), the incidence of numerical or clinical hypotony and adverse events were comparable in both groups (p > 0.05). The mean number of IOP-lowering medications was comparable in both groups at all time points.Conclusion: The X

Published
2022

36. Complete Genome Sequences of Five SO-1-Like Siphoviridae Bacteriophages That Infect Enterobacteriales

Author

Purnell, Madelyn G., primary, Andersen, Kyle, additional, Bell, Adam, additional, Briscoe, Jared T., additional, Brown, Hannah M. F., additional, Carr, Emilee L., additional, Doney, Justen, additional, Folsom, Parker F., additional, Green, Cheyanne, additional, Harris, Evan H., additional, Huhem, Elisa, additional, Jensen, R. Matthew, additional, Johnson, Liberty, additional, Jones, Carter, additional, Lambert, Andrew S., additional, Loertscher, Emily, additional, Newey, Colleen R., additional, Porter, Matthew, additional, Rallison, Jonah, additional, Sharma, Ruchira, additional, Sork, Carson, additional, Soule, Silvia, additional, Stewart, Jared B., additional, Stoker, Tyson, additional, Tayler, Sadie, additional, Thompson, Daniel W., additional, Thurgood, Trever L., additional, Walker, Jamison, additional, Breakwell, Donald P., additional, Casjens, Sherwood R., additional, and Grose, Julianne H., additional

Published
2022
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37. Excisional Goniotomy in Latino Patients with Open-Angle Glaucoma: Outcomes Through 24 Months

Author

Porter, Matthew, Garza, Arnulfo, and Gallardo, Mark

Subjects
Latino, glaucoma, excisional goniotomy, genetic structures, Kahook Dual Blade, Clinical Ophthalmology, Case Series, sense organs, eye diseases, intraocular pressure
Abstract

Matthew Porter,1,2 Arnulfo Garza,3 Mark Gallardo1 1Private Practice, El Paso Eye Surgeons, P.A., El Paso, Texas, USA; 2Texas Tech University Health Sciences Center School of Medicine-Lubbock, Lubbock, TX, USA; 3Texas Tech University Paul L. Foster School of Medicine, Lubbock, TX, USACorrespondence: Mark Gallardo Private Practice, El Paso Eye Surgeons, P.A., 1201 N. Mesa, Ste G, El Paso, TX 79902, USAEmail gallardomark@hotmail.comPurpose: To characterize the efficacy of combined phacoemulsification and excisional goniotomy with the Kahook Dual Blade (KDB-phaco) in eyes of Latino adults with cataract and open-angle glaucoma (OAG).Methods: Health records of consecutive Latino patients undergoing KDB-phaco were retrospectively reviewed. Intraocular pressure (IOP) and IOP-lowering medication use were recorded at baseline and each postoperative visit through up to 24 months. Primary outcomes were reductions in IOP and medication use from baseline; secondary outcomes were the proportions of eyes achieving IOP reductions of ≥ 20% and medication reductions ≥ 1 medication from baseline. Subgroup analysis was conducted in eyes with high and low baseline IOP.Results: Data from 44 eyes of 32 Latino patients with OAG were analyzed. Mean IOP was 17.8 (0.7) mmHg at baseline and postoperatively ranged from 12.4 to 13.8 mmHg (p≥ 0.0003), representing mean IOP reductions of 4.2– 4.6 mmHg (19.7– 23.1%). Mean medication was 1.5 (0.2) medications per eye at baseline and postoperatively ranged from 0.2 to 1.0 (p≥ 0.0061), representing mean medication reductions of 0.7– 1.2 medications per eye (47.1– 87.2%). In the low baseline IOP group (< 18 mmHg), mean IOP was significantly reduced through Month 24 and medications through Month 12; in the high baseline IOP group (≥ 18 mmHg), IOP and medications were significantly reduced through Month 24. From Months 1– 24, IOP reductions of ≥ 20% were achieved by 48.4– 56.2% of eyes in the full cohort, by 20.0– 33.3% in the low IOP group, and by 66.7– 100% in the high IOP group; medication reductions of ≥ 1 medication were achieved by 72.0– 95.6%, 64.7– 94.2%, and 87.5– 100% of eyes, respectively.Conclusion: Combined KDB-phaco in eyes of Latino patients with glaucoma and cataract significantly lowers IOP and the need for IOP-lowering medications for up to 24 months and should be considered for such patients who warrant IOP reduction, medication reduction, or both.Keywords: glaucoma, intraocular pressure, excisional goniotomy, Kahook Dual Blade, Latino

Published
2020

40. Computational Characterization of Microwave-Enhanced CVI Production of SiCf/SiC Composites

Author

Porter, Matthew, Binner, Jon, Kumi, Petra, Stern, Kevin, and Yakovlev, Vadim

Subjects
Energy coupling, microwave heating, modelling, SiC composites, temperature field
Abstract

Silicon carbide fiber reinforced silicon carbide matrix composites (SiCf/SiC) have been identified as a material with high-performance mechanical properties for the aerospace industry. Microwave-enhanced (ME) chemical vapor infiltration (CVI) heating of ceramic matrix has been proposed as an efficient production technique having the potential to yield near fully dense SiCf/SiC composites in a significantly shorter time span. This paper presents some results of computational analysis of electromagnetic and thermal characteristics of the ME CVI process carried out with thin SiC discs in a Labotron microwave system from SAIREM. The simulations are aimed to clarify multiple unexplained observations in experimental work through understanding causes for the formation of microwave-induced temperature fields. Resonant and non-resonant frequencies of the experimental system for different temperatures of the processed SiC sample are analyzed to explain the difference in heating rates. 3D temperature fields inthe SiC preforms at different frequencies are also presented. It is shown that, after being non-uniform in the beginning of the process, temperature patterns evolve to quite homogeneous ones by its end. The results suggest a means for better control of the equipment to pave the way to more efficient implementations of ME CVI the hence the less expensive and high quality SiCf/SiC composites.

Published
2021
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44. Implementation and Design of a Novel Student Developed Modular HTOL/HTRB System Using Thermoelectric Control

Author

O’Neal, Nathaniel J., Porter, Matthew A., Martino, Christopher Adrian, Naval Postgraduate School, and Electrical and Computer Engineering (ECE)

Abstract

2021 ASEE Virtual Annual Conference Content Access 17 USC 105 interim-entered record; under review. Addressing reliability issues is critical to the successful design and implementation of new semiconductor material systems proposed for next generation power electronic devices. For military systems, reliability is central to successful device designs, often outweighing other design factors. Several reliability testing schemes are central to validating power semiconductor device reliability. Of these, high temperature operating life (HTOL) and high temperature reverse bias (HTRB) testing are often used as go/no-go metrics for the success or failure of a fabricated lot of devices. To educate students in the importance of these testing regimens for devices, several undergraduate and graduate students have developed a custom, modular thermoelectrically cooled and controlled HTOL/HTRB system which allows for joint long term HTOL/HTRB testing at both institutions. Under constraints for cost, the system was designed to utilize a novel thermoelectric cooling scheme to provide a temperature range of 55 °C from 5 °C to 62 °C with less than 0.5 °C variation under 15 W heat load from devices-under-test (DUTs). A hermetic DUT environment was designed using nitrogen purging and active humidity sensing to control relative humidity (RH) within the environment to beneath 5% RH. Undergraduate students gained experience designing for manufacturability and machining with CAD tools not typically explored in typical electrical engineering design projects. An automated switch-matrix was designed and implemented to automate testing and allow for programming of complex stress-measure-stress reliability testing profiles. Control and automation was enabled using common MBED processors used throughout an undergraduate electrical engineering curriculum. To accomplish a unified design which could be installed at multiple locations, students investigated and implemented a server rack mounted design which uses commonly available banana and BNC connections for "plug-and-play" of the system. A control program was developed using a LabVIEW program which managed the system wide control and programming of different reliability testing regimens, such as stress-measure-stress, stepped-stress, and constant current, voltage, or power testing. Results for the fabricated system performance are shown demonstrating the successful achievement of the design metrics. To demonstrate the use of the system, results from recent undergraduate student led HTOL testing on novel GaN Schottky diode parts are presented. Current and future senior capstone and masters-level research projects using the novel system are reviewed.

Published
2021

45. A RELIABILITY STUDY ON THE EFFECTS OF HTOL AND HIGH-CURRENT DENSITY STRESS TESTING ON COMMERCIAL-GRADE VERTICAL N-TYPE PD/GAN SCHOTTKY DIODES

Author

Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), Clemmer, Burnell A., Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), and Clemmer, Burnell A.

Abstract

Traditional silicon-based power electronics have approached their performance limits for high-power electronic applications. The U.S. Navy is actively pursuing the implementation of wide bandgap (WBG) semiconductor materials to realize reliable devices for use in high-power, high-current, and high-voltage applications. Gallium nitride (GaN) is a promising candidate for these applications due to its inherent material properties, and recent efforts to produce high quality bulk GaN have begun to enable the production of commercial-grade devices. However, much is still unknown regarding the reliability of GaN devices, especially Schottky diodes, which are often affected by issues involving barrier height inhomogeneity (BHI). First, a stress testing system capable of taking in-situ current-voltage-temperature (I-V-T) measurements while applying electrical stress was constructed. Next, a sample of commercial-grade vertical n-type palladium/gallium nitride (Pd/GaN) Schottky diodes were subjected to a series of step current and constant current stress tests. Current densities above 1.3 kA/cm^2 were achieved. Finally, the effects of electrical stress on material properties were observed through comparison of pre-, post-, and in-situ I-V-T data. The in-situ I-V-T measurements enabled degradation to be observed as a function of stress time. Results show that significant degradation to the material properties of the Schottky diodes occurs within the first few hours of stress testing., Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Published
2021

46. POWER GAN SCHOTTKY DIODES UNDER CURRENT DENSITY STRESSING

Author

Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), Mund, Alexander G., Weatherford, Todd R., Porter, Matthew A., Electrical and Computer Engineering (ECE), and Mund, Alexander G.

Abstract

Silicon is commonly used in modern electronics; however, the technical specs are being maxed. Wide bandgap semiconductors such as gallium nitride (GaN) are being explored to further the development of better power electronics. This thesis continues testing conducted by Naval Postgraduate School student Burnell Clemmer, who designed a testing box capable of stressing wide bandgap semiconductors and found that they were failing quickly under stress. The objective of this thesis was to identify the range of operation for GaN Schottky diodes and their failure mechanisms under high current density stressing to allow for better designs for high voltage power diodes. In order to accomplish this, we conducted a series of high temperature operating life stress experiments by running an electrical current through representative bulk GaN power diodes for extended periods of time. We then documented their degradation by taking current-voltage-temperature characteristic plots throughout the test. The results generally showed that both time and current density increased the rate of degradation of the devices, but concrete conclusions could not be drawn due to limited amount of data and inconsistencies., Lieutenant, United States Navy, Approved for public release. Distribution is unlimited.

Published
2021

47. Implementation and Design of a Novel Student Developed Modular HTOL/HTRB System Using Thermoelectric Control

Author

Naval Postgraduate School, Electrical and Computer Engineering (ECE), O’Neal, Nathaniel J., Porter, Matthew A., Martino, Christopher Adrian, Naval Postgraduate School, Electrical and Computer Engineering (ECE), O’Neal, Nathaniel J., Porter, Matthew A., and Martino, Christopher Adrian

Abstract

Addressing reliability issues is critical to the successful design and implementation of new semiconductor material systems proposed for next generation power electronic devices. For military systems, reliability is central to successful device designs, often outweighing other design factors. Several reliability testing schemes are central to validating power semiconductor device reliability. Of these, high temperature operating life (HTOL) and high temperature reverse bias (HTRB) testing are often used as go/no-go metrics for the success or failure of a fabricated lot of devices. To educate students in the importance of these testing regimens for devices, several undergraduate and graduate students have developed a custom, modular thermoelectrically cooled and controlled HTOL/HTRB system which allows for joint long term HTOL/HTRB testing at both institutions. Under constraints for cost, the system was designed to utilize a novel thermoelectric cooling scheme to provide a temperature range of 55 °C from 5 °C to 62 °C with less than 0.5 °C variation under 15 W heat load from devices-under-test (DUTs). A hermetic DUT environment was designed using nitrogen purging and active humidity sensing to control relative humidity (RH) within the environment to beneath 5% RH. Undergraduate students gained experience designing for manufacturability and machining with CAD tools not typically explored in typical electrical engineering design projects. An automated switch-matrix was designed and implemented to automate testing and allow for programming of complex stress-measure-stress reliability testing profiles. Control and automation was enabled using common MBED processors used throughout an undergraduate electrical engineering curriculum. To accomplish a unified design which could be installed at multiple locations, students investigated and implemented a server rack mounted design which uses commonly available banana and BNC connections for "plug-and-play" of the system. A con

Published
2021

48. GaN LIGHT EMISSION FOR CONTROL SYSTEM FEEDBACK

Author

Weatherford, Todd R., Corzine, Keith, Porter, Matthew A., Electrical and Computer Engineering (ECE), Williams, Johnathan L., Weatherford, Todd R., Corzine, Keith, Porter, Matthew A., Electrical and Computer Engineering (ECE), and Williams, Johnathan L.

Abstract

This work explores previous research showing the correlation of light emission to current and temperature in a gallium nitride (GaN) vertical diode to predict current within a power converter circuit. Use of light emissions to measure current would offer an improvement over present sensors, since light would not be affected by the EMI found in most switched power converters. Matrices of the light emissions at 370, 380, 390, 400, 440, and 550 nm wavelengths over a range of 0.2 A to 4 A and 20 °C to 110 °C were used to develop best-fit polynomials for each matrix. Two of these polynomials can then be utilized to derive a unique solution of current and temperature based on the light output at the distinct wavelengths. Lock-in amplifiers allowed the amplification of weak light signals without gain bandwidth product limitations. Future efforts will be to duplicate the lock-in amplifier as well as the current and temperature prediction with use of a microcontroller.

Published
2020

49. OPTIMIZATION OF MULTI-JUNCTION SOLAR CELL FOR SPACE APPLICATIONS MODELED WITH RUBY, MATLAB, AND SILVACO

Author

Michael, Sherif N., Porter, Matthew A., Electrical and Computer Engineering (ECE), Allen, Tony Jr., Michael, Sherif N., Porter, Matthew A., Electrical and Computer Engineering (ECE), and Allen, Tony Jr.

Abstract

The purpose of this research is to document further research into the optimization techniques investigated by James Walsh and applied to Multi-junction Solar Cells. Walsh performed his research with the Near Orthogonal Latin Hypercube (NOLH) in order to optimize the design specifications for each layer of solar cell thickness and doping concentration. Walsh at the same time evaluated cell performance under the radiation effects of the space environment. This research performed a similar analysis, except for the radiation effects, but focused more on producing an algorithm that could be executed from single user input and significantly reducing the selected design space. This research produced an efficient program that seamlessly operates between Ruby, MATLAB, and Silvaco ATLAS in order to produce an optimal designed dual-junction solar cell for space applications, in a much smaller design space than the technique utilized by Walsh., http://archive.org/details/optimizationofmu1094564137, Captain, United States Marine Corps, Approved for public release; distribution is unlimited.

Published
2020

50. ANALYSIS OF RADIATION EFFECTS ON GALLIUM NITRIDE ZIRCONIUM OXIDE METAL OXIDE SEMICONDUCTOR CAPACITORS

Author

Weatherford, Todd R., Anderson, Travis , U.S. Naval Research Laboratory, Porter, Matthew A., Electrical and Computer Engineering (ECE), Reasoner Blasch, Connor M., Weatherford, Todd R., Anderson, Travis , U.S. Naval Research Laboratory, Porter, Matthew A., Electrical and Computer Engineering (ECE), and Reasoner Blasch, Connor M.

Abstract

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.

Published
2020

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