Sylvia Thomas

Atomic layer deposition of Pb(Zr,Ti)Ox on 4H-SiC for metal-ferroelectric-insulator-semiconductor diodes

Atomic layer deposited (ALD) Pb(Zr,Ti)Ox (PZT) ultra-thin films were synthesized on an ALD Al2O3 insulation layer on 4H-SiC substrate for metal-ferroelectric-insulator-semiconductor (MFIS) device applications. The as-deposited PZT was amorphous but crystallized into a perovskite polycrystalline structure with a preferred [002] orientation upon rapid thermal annealing (RTA) at 950 °C. The capacitance-voltage and current-voltage characteristics of the MFIS devices indicate carrier injection to the film induced by polarization and Fowler-Nordheim (FN) tunneling when electric field was high. The polarization-voltage measurements exhibited reasonable remanent and saturation polarization and a coercive electrical field comparable to that reported for bulk PZT. The piezoresponse force microscope measurements confirmed the polarization, coercive, and retention properties of ultra-thin ALD PZT films.

COM2 SiGe modular BiCMOS technology for digital, mixed-signal, and RF applications

The COM2 SiGe modular BiCMOS technology has been developed to allow efficient design and manufacturing of digital, mixed-signal, and RF integrated circuits, as well as enabling system-on-chip (SOC) integration. The technology is based on the 0.16 /spl mu/m COM2 digital CMOS process which features 1.5 V NMOS and PMOS transistors with 2.4 nm gate oxide, 0.135 /spl mu/m gate length, and up to 7 metal levels. Technology enhancement modules including dense SRAM, SiGe NPN bipolar transistor, and a variety of passive components have been developed to allow the COM2 technology to be cost-effectively optimized for a wide range of applications.

Microfluidic hydrothermal growth of ZnO nanowires over high aspect ratio microstructures

A hydrothermal synthesis of densely packed ZnO nanowires was realized in a confined space via forced circulation of the heated growth solution through microfluidic channels formed primarily by a set of high aspect ratio trenches in a Si substrate. A uniform and conformal seeding layer of ZnO was deposited to cover the entire surface of the trenches by means of atomic layer deposition (ALD). Densely packed ZnO nanowires were formed inside the trenches with particularly good coverage over the sidewalls, where they would not grow effectively through a conventional hydrothermal method. The strategy for controlled growth of densely packed ZnO nanowires over such high aspect ratio microstructures is deemed beneficial when these microstructures are employed as electrodes with high specific surface areas for devices such as supercapacitors or any other electrochemical devices.

SiC for Biomedical Applications

Silicon carbide is a well-known wide-band gap semiconductor traditionally used in power electronics and solid-state lighting due to its extremely low intrinsic carrier concentration and high thermal conductivity. What is only recently being discovered is that it possesses excellent compatibility within the biological world. Since publication of the first edition of Silicon Carbide Biotechnology: A Biocompatible Semiconductor for Advanced Biomedical Devices and Applications five years ago [1], significant progress has been made on numerous research and development fronts. In this paper three very promising developments are briefly highlighted – progress towards the realization of a continuous glucose monitoring system, implantable neural interfaces made from free-standing 3C-SiC, and a custom-made low-power ‘wireless capable’ four channel neural recording chip for brain-machine interface applications.

Cobalt-Doped Antimony/Tin Oxide Sol–Gels on Carbon–Silicon Layers for Modeling Sol–Gel-Carbon Fiber Interfaces

This research presents a novel thermo-responsive sol–gel (dopant) combination and evaluation of the actuating responses due to various heat treatment temperatures. In this project, samples of antimony-doped tin oxide (ATO) doped with 0.1% cobalt oxide (0.1% Co2O3) sol–gel on carbon/silicon substrates are used to model the implementation of sol–gel coatings into carbon fiber composite systems. While ATO is a well-known transparent conductive material, the addition of cobalt oxide (Co2O3) alters its morphology and optical parameters at low annealing temperatures. By altering the ATO (0.1% Co2O3) heat treatment temperatures, the grain size starts to increase at 200 °C. However, when approaching 500 °C, Raman spectroscopy shows that the increase in intensity of ATO (0.1% Co2O3) is lower than ATO undoped. Scanning electron microscopy is used for imaging, and energy dispersive spectroscopy will be used for the composition analysis. Optical reflectance is reported via Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy analysis.

3C-SiC on Si: A bio- and hemo-compatible material for advanced nano-bio devices

Silicon carbide (SiC) has long been known as a robust semiconductor with superior properties to silicon for electronic applications. The cubic form of SiC, known as 3C-SiC, has been researched for non-electronic applications, such as MEMS and biosensors. In particular, our group has demonstrated that 3C-SiC is one of the few semiconductor materials that possesses both bio- and hemacompatibility, thus opening up a plethora of applications for this material. We have pioneered several biomedical devices using 3C-SiC grown on Si substrates, and recently have been investigating the use of this novel material for both biosensor and neural prosthetic applications. Research to develop suitable biosensors, mainly via surface functionalization of 3C-SiC surfaces, has shown that 3C-SiC can be functionalized in much the same was as Si. We review nearly a decade of activity in 3C-SiC on Si biotechnology, with particular emphasis on the most promising applications: surface functionalization, in-vivo glucose sensing and biomedical implants for connecting the human nervous system to advanced prosthetics.

Learning Through Collaboration

In 2009, the Alliance for the Advancement of Florida’s Academic Women in Chemistry and Engineering (AAFAWCE, 2013), an energetic and talented team of academic women from the science, technology, engineering and mathematics (STEM) and social science disciplines, embarked on an ambitious project to increase the recruitment, retention, and advancement of academic women at our five Florida universities: University of South Florida (USF, lead institution), Florida State University (FSU), University of Florida (UF), Florida International University (FIU), and Florida Agricultural and Mechanical University (FAMU). Acquainted with each other through a previous NSF-funded research project, we developed a strong bond as we relied on each other for emotional and practical support, advice, and guidance as we encountered and overcame challenges as a collaborative team as well as on our respective campuses. In addition to becoming personally enriched through this collaboration, we witnessed the women and the men faculty who participated in our AAFAWCE activities growing professionally and personally over the four years. In this final chapter, we present the lessons learned from our AAFAWCE experiences.

Mentoring Women STEM Faculty

Academies, government agencies, industries, and research clearinghouses have asserted that “mentoring” is a critical strategy in the progression of organizational success. With success come obligations, responsibilities, commitments, and vision on the part of academic administrators, inter/intra departmental chairs/heads, colleagues, mentors, and proteges. Even more prevalent is the role that mentoring can play in an institution’s strategic vision toward progress for equity and for inclusion in research, teaching, and community engagement, particularly for women faculty in the science, technology, engineering, and mathematics (STEM) disciplines. A plethora of information, investigations, testimonies, and assessments exist that detail ways mentoring in an academic climate can foster career and institutional benefits on a global level (Hall & Sandler, 1983; Hunt & Michael, 1983; Jacobi, 1991; Merriam, 1983). Women faculty, postdoctoral researchers, and graduate students who work in environments that support mentoring have enhanced the probability of their career success and growth. A STEM environment that embraces all faculty, men, women, and other underrepresented groups, can sustain and enhance technical innovation, provide multiple perspectives on critical issues, and promote a more transformative and collaborative workplace (Adams, 1998a; Adams, 2002; Handlesman et al., 2005). Today, mentoring is recognized as a strategy for nurturing, developing, and empowering individuals to contribute their creativity, knowledge, and skills to the vision of the organization. The mentoring process has many styles, forms, and functions, but one aspect of the process holds true to form and that is “professional growth,” whether realized from a successful or not so successful mentoring relationship. The mentoring strategy can involve one or more mentors and a protege. The foundation of an effective mentoring relationship is the mentorship alliance between a mentor and a protege. In such an alliance, the mentor functions as a coach, teacher, role model, and even an advocate, and is the more experienced individual. The protege (i.e., mentee) is the “one who is under the care and protection of an experienced, influential, and prominent mentor, who seeks to help further the protege’s career” (Adams, 1998b). Even though mentoring has been employed by many academic institutions over the last decade and supported by many entities, the impact on the success of women faculty in STEM fields still needs strengthening. One of the key findings in the 2010

Optimized power management circuit for RF energy harvesting system

For many years, RF wireless harvesting systems have been investigated, but only a few of RF sources have been able to generate sufficient energy that can be used as feasible source for ultra low power applications. However, most of power management systems are not efficient at ultra low power sources like RF sources due to power consumption in control circuitry. The solution for this issue can be either power consumption reduction which is limited by physical constraints or another energy source in order to harvest enough power able to deliver it to the load. This Paper presents an optimized power management circuit to improve the efficiency of DC-DC converter, this is accomplished using particle swarm optimization technique, where the converter efficiency is used as the fitness function and inductor and on-time are chosen as optimized parameters. This design improves the DC-DC converter efficiency and the efficiency of optimized power management circuit by 9.25% comparing with conventional power management circuits over a wide range of input power, allowing harvesting more power from RF sources and delivering it to load. This approach is not limited to ultra low power applications; it can easily be extended in portable applications to extend the battery life.

Optimized mini notched turbine energy harvesting using resistor emulation approach and Particle Swarm Optimization

This paper proposes a novel mini notched turbine that can be used as a feasible energy source, and a methodology for optimizing the maximum-power-point tracking system needed to improve the efficiency of the DC-DC converter that helps transform the harvested kinetic energy coming from the turbine into useful electrical power. This methodology implemented by using a particle swarm optimization technique, where the converter efficiency is used as the fitness function, leading to optimized inductor and on-time parameter values. The proposed design improves the DC-DC converter efficiency by 9.25% when compared to conventional maximum-power-point tracking systems over a wide range of input power and optimal load resistances, allowing for the harvesting of more energy and greater power delivered to the load. This approach is not limited to ultra-low power applications; it can easily be extended to portable applications to extend battery life.