Brian William Goodfellow Department of Chemical Engineering Advisor: Brian Korgel First IGERT Semester: Fall 2006 Completed: Summer 2008 IGERT Project Focus: Development of Cu(InxGa1-x)Se2 (CIGS) nanocrystal-based photovoltaics Alexander Ako Khajetoorians Department of Physics Advisor: Chih-Kang Shih; Co-Advisor: Allan Macdonald First IGERT Semester: Fall 2006 Completed: Summer 2008 IGERT Project Focus: STM/STS of Dilute Magnetic Semiconductors and III-V interfaces Alfred Kwon-Hoon Lee Department of Physics Advisor: Alex de Lozanne First IGERT Semester: Fall 2006 Completed: Summer 2008 IGERT Project Focus: My research involves the study of complex metal oxides using low temperature AFM and STM. In particular, we are interested in observing magnetic and electric domain structure and phase transitions through varying temperatures and fields using our home built multi-mode AFM. Our UHV STM has also been fruitful in investigating the electronic structure of these materials at low temperatures. Han-Jong Chia Department of Physics Advisor: John Markert First IGERT Semester: Spring 2007 Completed: Fall 2008 IGERT Project Focus: I received a BA in economics and physics at Grinnell College and am currently pursuing a PhD in physics at the University of Texas at Austin. My research, under the guidance of Professor John Markert, is developing magnetic resonance force microscopy (MRFM) to study the properties of thin films. MRFM is a scanning probe microscopy technique that combines the cantilever based detection of atomic force microscopy (AFM) and pulsed magnetic fields of nuclear magnetic resonance (NMR). The synthesis of these two techniques yields nanometer scale spin resolution of various materials. I will use MRFM to obtain 3D spin images and relaxation times of organic and inorganic electronic materials. Down the road I intend to perform single nuclear spin detection feasibility studies by implementing high sensitivity cantilevers, novel forms of active feedback control, and millikelvin temperatures. Shannon Doane Lewis Department of Electrical and Computer Engineering Advisor: Ananth Dodabalapur First IGERT Semester: Spring 2007 IGERT Project Focus: Shannon Doane Lewis is a third year graduate student in Electrical and Computer Engineering (Solid State Electronics). She works for Professor Ananth Dodabalapur in the area of integrated organic and inorganic field effect transistors for chemical vapor sensing. She graduated from the California Institute of Technology with a degree in Chemical Engineering in 2005. Robert Alan May Department of Chemistry and Biochemistry Advisor: Keith Stevenson First IGERT Semester: Spring 2007 IGERT Project Focus: The study of optical properties of mixed MoxW1-xO3 thin films showing a grain size dependence of the optical band gap related to quantum size effect. Using the optical constants derived from spectroscopic ellipsometry one can determine the band gap and porosity of mesoporous TiO2 films as well as the orientation of Au nanocrystals electrophoretically fused into those same films. Benjamin Spivey Department of Chemical Engineering Advisor: John Ekerdt; Co-Advisor: Thomas Edgar First IGERT Semester: Spring 2007 IGERT Project Focus: My research project is focused on the growth of semiconducting vertical nanowires for use as chemical sensors. Currently, we have an APCVD system that has proven successful in growing vertical nanowires. Further research is expected to involve modeling the nanowire growth process, improving process control, and developing the nanowire pattern into an electrical sensing device. Neliza León Department of Materials Science and Engineering Advisor: Alex de Lozanne First IGERT Semester: Summer 2007 IGERT Project Focus: Novel methods of optimizing a fiber optic interferometer for cantilever motion detection by using a setup that allows alignment along three coordinate axes and two angles. She has been able, for the first time, to permanently attach AFM cantilevers directly to the end of an optical fiber after the five-variable adjustment to optimize the detection signal. Once the attachment is done, the fiber/cantilever is a robust single unit that can be moved or even cooled to liquid helium temperatures, where most of our scanning microscopes work. Daniel Birt Department of Materials Science and Engineering Advisor: Elaine Li First IGERT Semester: Fall 2007 IGERT Project Focus: The dynamics of spin torque transfer induced spin waves in thin magnetic multilayers using Brillouin Light Scattering Spectroscopy. Justin Harris Department of Chemical Engineering Advisor: Brian Korgel First IGERT Semester: Fall 2007 IGERT Project Focus: The use of nanoparticles in photovoltaic devices. Current focus is on all-nanoparticle p-InP/n-CdS heterojunction devices. All-nanoparticle thin film devices provide a less expensive alternative to traditional single-crystalline photovoltaic devices, important during our current energy crisis. Synthesis of the nanoparticles and formation of the thin films have been studied with TEM, SEM, XRD, and four-point electrical probe. Justin also collaborated with IGERT Trainee Brian Goodfellow and an interdisciplinary team on the investigation of nanoparticle CIGS photovoltaic devices. Michael Ramon Department of Electrical Engineering Advisor: Sanjay Banerjee; Co-Advisor: Miguel Yacaman First IGERT Semester: Fall 2007 IGERT Project Focus: The fabrication of self-aligned inversion-type enhancement-mode (E-mode) GaAs metal-oxide-semiconductor field-effect transistors (MOSFETs) with atomic layer deposition (ALD) of Al2O3 dielectric directly on GaAs substrates using an ex-situ wet clean of GaAs. Thermal stability of the gate stack was first examined by monitoring frequency dispersion behavior of GaAs MOS capacitors at elevated annealing temperatures, indicating excellent thermal stability of the interface. The stability of the of Al2O3/GaAs interface made transistor fabrication possible, and the demonstration of the inversion-type E-mode GaAs MOSFET substantiates the effectiveness of the ex-situ chemical cleaning treatment of GaAs substrates in improving the high-?/GaAs interface. Daniel Ratchford Department of Physics Advisor: Elaine Li First IGERT Semester: Fall 2007 IGERT Project Focus: In our lab, we study the quantum dynamics of composite nanostructures using a variety of optical spectroscopy techniques (e.g. micro-PL, pump and probe, and 2D Fourier transform).  Self-assembled composite materials allow for the design of unique materials with integrated and tunable properties.  Because of complicated interactions between components, the properties of the composite material may not be derived from the properties of the individual components.   A basic understanding of the quantum mechanics will aid in the design of new and improved structures.  Currently, we are studying a bio-conjugated semiconductor and metallic nanostructure focusing on how exciton and plasmon interactions affect its optical properties. [view resarch plan] Omar Fabian Department of Materials Science and Engineering Advisor: Paul Barbara First IGERT Semester: Fall 2008 IGERT Project Focus: Currently working with Dr. Paul Barbara in trying to understand the wave-like behavior of electrogenerated chemiluminescence (ECL) stimulated in single molecule spectroelectrochemical (SMS-EC) cells containing conjugated polymer nanoparticles. This involves study of ECL phenomena in SMS-EC cells and associated electrochemical kinetics to develop a suitable model for describing the observed ECL wavefront in terms of mass transport, diffusion, and surface kinetics. Micah Glaz Department of Chemistry and Biochemistry Advisor: David Vandenbout First IGERT Semester: Fall 2008 IGERT Project Focus: My research focuses on near-field scanning optical microscopy (NSOM), which allows for topographical information and optical resolution near 50-100nm. Currently, we are studying thin film organic solar cells in order to spatially resolve the phase segregation of polymer blends as a function of photocurrent, time-resolved fluorescence, and efficiency. Along with these studies, we are also interested in using confocal microscopy to resolve efficient and inefficient areas in inorganic photovoltaic devices. John Robertson Department of Physics Advisor: Ken Shih First IGERT Semester: Fall 2008 IGERT Project Focus: My research involves the study of spectroscopic properties of Quantum Dots qrown inside micro-cavity structures. We are currently studying their emission properties using time correlation measurements when they are excited resonantly using a narrow line laser source. We hope to soon perform optical experiments using Quantum Dots in new novel Photonic Crystal microcavities which will serve as the next step in developing efficient single photon sources. John Adam Stephens Department of Chemical Engineering Advisor: Gyeong Hwang First IGERT Semester: Fall 2008 IGERT Project Focus: My research focuses on how the catalytic activity of single-metal and alloy nanoparticles is influenced by their size, composition, shape, and support. In this work, I use a combination of density functional theory and an array of classical, atomistic simulation techniques. Chris Mann Department of Materials Science and Engineering Advisor: Ken Shih First IGERT Semester: Fall 2009 IGERT Project Focus: Development of a platform for transport scanning tunneling microscopy (STM) and studies of confined electronic systems. STM techniques are well established for studying the electronic structure of materials. With the addition of in situ electronic transport measurements, substantially more can be learned about the materials than is possible with standard methods. Examples of confined electronic systems of interest include few-atom thick layers of metals, graphene, and various semiconductor structures. Jason Mantey Department of Electrical and Computer Engineering Advisor: Sanjay Banerjee First IGERT Semester: Fall 2009 IGERT Project Focus: My work focuses on the growth of semiconductor nanowires using a top-down approach. Nano-imprint lithography is used to pattern silicon wafers with an array of nanowire seed locations. Then ultra-high vacuum chemical vapor deposition is used to grow silicon-germanium or germanium nanowires with diameters of less than 100nm. High-k dielectrics and metal connections will be added later to create vertical transistors from clusters of the nanowires. By clustering many wires together, a higher width to length ratio can be obtained, which can raise drive current and improve device performance without sacrificing large amounts of wafer surface area. Charlotte Sanders Department of Physics Advisor: Ken Shih, Co-advisor: Mark Raizen First IGERT Semester: Summer 2009 IGERT Project Focus: Epitaxial growth of single-crystal thin films and the fabrication of novel metal-semiconductor hybrid structures for plasmonics investigations. Sarah Stranahan Department of Chemistry Advisor: Katherine Willets First IGERT Semester: Fall 2009 IGERT Project Focus: Organic fluorescent dyes are widely used in biological labeling experiments and single molecule spectroscopy. These fluorophores eventually photobleach into a non-emissive state rendering them useless for their experimental purpose. My research is working on understanding the structural changes that accompany photobleaching by using a combined approach of surface-enhanced Raman scattering (SERS), mass spectrometry, and electronic structure calculations. Morgann Berg Department of Physics Advisor: Alex de Lozanne First IGERT Semester: Fall 2009 IGERT Project Focus: My research revolves around probing the limitations of real charge density mapping via Scanning Probe Microscopy(SPM). Optimization of charge density mapping will depend mainly upon analytical methods used to interpret the data and probe tip characterization. To that end, different computational analysis methods will be compared and the effect of using carbon nanotubes as probe tips will be investigated. Examination of charge ordering in transition metal oxide compounds with interesting electronic and magnetic behavior(e.g. colossal magnetoresistance, non-conventional superconductivity, etc.) will provide rich data, a means to acuminate this less-explored SPM technique and better understand the contributions of electronic degrees of freedom to exotic phenomena in condensed matter systems. Guru Khalsa Department of Physics Advisor: Allan MacDonald First IGERT Semester: Fall 2009 IGERT Project Focus: Transition Metal Oxide Heterostructures. Julian Villarreal Department of Materials Science Engineering Advisor: Brian Korgel First IGERT Semester: Summer 2010 IGERT Project Focus: One of the Korgel group's core competencies is the synthesis of high-quality Si nanowires (SiNWs) in amounts of tens of milligrams per batch by the supercritical fluid-liquid-solid (SFLS) growth method. I am currently endeavoring to dope SiNWs with phosphorus (n-type doping) in the context of the SFLS method. Characterization of phosphorus incorporation into the SiNWs is accomplished using low-temperature Electron Paramagnetic Spin Resonance (EPR) spectroscopy. Further characterization of the SiNWs themselves is done via TEM, SEM, and three-point probe FET measurements. The hope is that n-type doping will enhance charge carrier mobility in the SiNWs, which would be advantageous for applications such as field effect Karole Blythe Department Chemistry and Biochemistry Advisor: Kallie Willets First IGERT Semester: Fall 2010 IGERT Project Focus: Nobel metal particles have become very important in a wide variety of fields because they can support a plasmon which creates enhanced electromagnetic fields around the particle. These enhanced fields can be utilized in a variety of research arenas, including medical and catalysis research as well as surface enhanced spectroscopy techniques. My research focuses on using super resolution imaging, specifically stochastic optical reconstruction microscopy, as a technique for mapping out the precise location of these enhanced fields as well as gain size and shape information about the nanoparticle. David Dillen Department of Electrical & Computer Engineering Advisor: Emanuel Tutuc First IGERT Semester: Fall 2010 IGERT Project Focus: Core-shell nanowire heterostructures have been recognized as an attractive geometry for the extension of field-effect transistor scaling past the limits of what is possible with current planar devices. This configuration leads to an enhancement in carrier mobility through the confinement of electrons/holes into the core of the nanowire, spatially separating them from trap states at the semiconductor-insulator interface. Until recently, the effects of lattice mismatch strain in such a structure have been ignored. My research focuses on determining the interaction between this mechanical strain and the electrical transport properties in germanium/silicon based core-shell nanowires. Specifically, I am interested in the magnitude of band offset between the core and shell of such a structure, along with strain-enhanced reductions in intervalley scattering rate and carrier effective mass.