Nanoscience and Nanotechnology Commons^™

Metal-Assisted Etching Of Silicon Molds For Electroforming, Ralu Divan, Dan Rosenthal '14, Karim Ogando, Leonidas E. Ocola, Daniel Rosenmann, Nicolaie Moldovan

Student Publications & Research

Ordered arrays of high-aspect-ratio micro/nanostructures in semiconductors stirred a huge scientific interest due to their unique one-dimensional physical morphology and the associated electrical, mechanical, chemical, optoelectronic, and thermal properties. Metal-assisted chemical etching enables fabrication of such high aspect ratio Si nanostructures with controlled diameter, shape, length, and packing density, but suffers from structure deformation and shape inconsistency due to uncontrolled migration of noble metal structures during etching. Hereby the authors prove that a Ti adhesion layer helps in stabilizing gold structures, preventing their migration on the wafer surface while not impeding the etching. Based on this finding, the authors demonstrate …

Graphene Quantum Dots Enhanced Electrochemical Performance Of Polypyrrole As Supercapacitor Electrode, Kun Wu, Si-Zhe Xu, Xue-Jiao Zhou, Hai-Xia Wu

Journal of Electrochemistry

With an objective to develop electrode materials with high specific capacitance and good stability, a completely new nanocomposite of Polypyrrole (PPY) and graphene quantum dots (GQD) was successfully obtained through in-situ polymerization of pyrrole in the presence of GQD suspension. The obtained composites with different mass ratios were characterized by X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). GQD enhanced electrochemical performance of PPY and, as supercapacitor electrodes, the PPY/GQD composites with the mass ratio of PPY to GQD at 50:1 showed a competitive specific capacitance of 485 F·g^-1 at a scan rate of …

Effects Of Nanocrystal Shape And Size On The Temperature Sensitivity In Raman Thermometry, Liangliang Chen, Kelly Rickey, Qing Zhao, Christopher Robinson, Xiulin Ruan

Birck and NCN Publications

The effects of CdSe nanocrystal (NC) shape and size on the temperature sensitivity of the Raman shift have been investigated, for the interest of Raman thermometry using NCs. For spherical CdSe NCs of diameters 2.8 nm, 3.6 nm, and 4.4 nm, the temperature sensitivities are -0.0131 cm(-1)/K, -0.0171 cm(-1)/K, and -0.0242 cm(-1)/K, respectively. This trend indicates that as the diameter increases, the effect of increasing phonon anharmonicity dominates over the effect of the decreasing thermal expansion coefficient. On the other hand, triangular NCs with a size of 4.2 nm and elongated NCs of a dimension of 4.6 nm by 14 …

Electronic And Optical Properties Of Scn And (Sc,Mn)N Thin Films Deposited By Reactive Dc-Magnetron Sputtering, Bivas Saha, Gururaj V. Naik, Vladimir P. Drachev, Alexandra Boltasseva, Ernesto Marinero, Timothy D. Sands

Birck and NCN Publications

Scandium nitride (ScN) is a rocksalt semiconductor that has attracted significant attention from various researchers for a diverse range of applications. Motivated by the prospect of using its interesting electronic structure for optoelectronic and dilute magnetic semiconductor applications, we present detailed studies of the electronic transport and optical properties of ScN and its alloys with manganese nitride (MnN). Our results suggest (a) dilute manganese doping in ScN compensates for the high n-type carrier concentrations arising due to oxygen impurities and (b) an n-type to p-type carrier type transition occurs at a composition between 5.8% and 11% Mn on Sc sites. …

Frequency Response Of Atmospheric Pressure Gas Breakdown In Micro/Nanogaps, Abbas Semnani, Ayyaswamy Venkattraman, Alina A. Alexeenko, Dimitrios Peroulis

Birck and NCN Publications

In this paper, we study gas breakdown in micro/nanogaps at atmospheric pressure from low RF to high millimeter band. For gaps larger than about 10 mu m, the breakdown voltage agrees with macroscale vacuum experiments, exhibiting a sharp decrease at a critical frequency, due to transition between the boundary- and diffusion-controlled regimes, and a gradual increase at very high frequencies as a result of inefficient energy transfer by field. For sub-micron gaps, a much lower breakdown is obtained almost independent of frequency because of the dominance of field emission. (C) 2013 AIP Publishing LLC.

Mapping The 3d Surface Potential In Bi2se3, Chris Mann, Damien West, Ireneusz Miotkowski, Yong P. Chen, Shengbai Zhang, Chih-Kang Shih

Birck and NCN Publications

Bi2Se3 initially emerged as a particularly promising host of topological physics. However, in actual materials, several issues have been uncovered including strong surface band bending and potential fluctuations. To investigate these concerns, we study nominally stoichiometric Bi2Se3 using scanning tunnelling microscopy. Here we identify two distinct distributions of Bi-Se antisites that act as nanometer-scale sensors for the surface band-bending field. To confirm this, we examine bulk Cu-doped Bi2Se3 and demonstrate a significantly reduced surface band-bending field. In addition, we find that in the case of unintentionally doped Bi2Se3, lateral fluctuations of the Dirac point can be directly correlated with specific …

A Humidity-Sensitive Hydrogel-Bacillus Spore Composite For Micropatterning Of Biomolecular Gradients, Richard L. Gieseck, Bin-Da Chan, Cagri A. Savran

Birck and NCN Publications

A composite material consisting of Bacillus subtilis spores suspended in a humidity sensitive hydrogel can be used to pattern biomolecules in different concentrations directly onto glass surfaces using a mechanical micromanipulator. By altering the relative humidity surrounding the composite gel during deposition, surface concentration of patterned biomolecules can be controlled and varied to create user-defined, biomolecular surface concentrations. (C) 2013 AIP Publishing LLC.

Theranostic Nanoparticles For The Treatment Of Cancer, Thomas Moore

All Dissertations

The main focus of this research was to evaluate the ability of a novel multifunctional nanoparticle to mediate drug delivery and enable a non-invasive approach to measure drug release kinetics in situ for the treatment of cancer. These goals were approached by developing a nanoparticle consisting of an inorganic core (i.e. gadolinium sulfoxide doped with europium ions or carbon nanotubes). This was coated with an external amphiphilic polymer shell comprised of a biodegradable polyester (i.e. poly(lactide) or poly(glycolide)), and poly(ethylene glycol) block copolymer. In this system, the inorganic core mediates the imaging aspect, the relatively hydrophobic polyester encapsulates hydrophobic anti-cancer …

Synthesis Of Platinum And Platinum-Copper Branched Nanoparticles For Electrooxidation Of Methanol, Eric Courtland Taylor

Graduate Theses and Dissertations

Platinum and Pt alloys are among the most important heterogeneous catalysts for many organic reactions and electrochemical reactions associated with the fuel cell technologies. How to reduce Pt usage while maintaining the performance of the catalysts becomes a subject for intensive research in materials chemistry. For heterogeneous catalysis, the catalytic reactivity and selectivity are strongly correlated with different crystallographic facets exposed on the surface. The facets with high-index planes whose Miller indices with at one is larger than unity are generally more active than those with low-index planes (e.g., {100}, {111}, and {110}). Tuning the morphology of the nanoparticles to …

Pan Nanofibers And Nanofiber Reinforced Composites, Cheng Ren

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Nanomaterials play an important role in the development of nanotechnology. They possess unique mechanical, physical, and chemical properties coupled with small size and ultrahigh surface area that can provide critical advantages for applications. Continuous nanofibers attract special interest due to their dual nano-macro nature and ability to bridge scales. Nanofibers are being considered for a broad range of applications spanning advanced filters, separation membranes, ultrasensitive sensors, micro/nano actuators, nanoprobes, tissue engineering scaffolds, protective and smart closing, and multifunctional composites. Most of these applications require certain mechanical properties and robustness. However, the literature on the mechanical behavior of nanofibers and their …

The Legitimation Of Novel Technologies: The Case Of Nanotechnology, Anastasia E. Thyroff

Graduate Theses and Dissertations

Nanotechnology is the control, manipulation, and application of matter on an atomic and molecular level. The technology is complex and confusing to consumers, and its long-term safety and effect on the human body, as well as the environment, are unknown. However, for the past decade, nanotechnology has been used to develop consumer products and food with novel and attractive attributes.

Since nanotechnology is still not well known, it is not legitimized; that is, it has not been deemed safe and accepted by society. However, the market for nanotechnology is in the legitimation process. It will take an entire network of …

Structural Properties Of Ferroelectric Lead (Zirconium0.5,Titanium0.5)Oxygen3 Nanotube Array And Electronic Structure Of Lao Delta-Doped Strontium Titanate, Rajendra Prasad Adhikari

Graduate Theses and Dissertations

In this Dissertation we begin with two introductions on: 1) ferroelectricity and related phenomena, and 2) novel properties of Oxide electronics and the generation of two dimensional electron gas. We then give theoretical background of density functional theory (including LDA+U) and pseudopotentials. The first part of research work is about structural, polarization, and dielectric properties of ferroelectric Lead Zirconate Titanate (PZT) solid solution in the form of a nanotube array, embedded in a matrix medium of different ferroelectric strengths. We use the effective Hamiltonian derived from first-principles and finite-temperature Monte Carlo methods to determine the various properties. We revealed different …

Multiscale Study Of Batio3 Nanostructures And Nanocomposites, Lydie Louis Louis

Graduate Theses and Dissertations

Advancements in integrated nanoelectronics will continue to require the use of unique materials or systems of materials with diverse functionalities in increasingly confined spaces.

Hence, research on finite-dimensional systems strive to unearth and expand the knowledge of fundamental physical properties in certain key materials which exhibit numerous concurrent and exploitable functions.

Correspondingly, ferroelectric nanostructures, which particularly display a plethora of complex phenomena, prevalent in countless fields of research, are noteworthy candidates. Presently, however, the assimilation of zero-(0D) and one-dimensional (1D) ferroelectric into micro- or nano-electronics has been lagging, in part due to a lack of applied and fundamental studies but …

Hysteretic Response Of Chemical Vapor Deposition Graphene Field Effect Transistors On Sic Substrates, Edward Cazalas, Isaac Childres, Amanda Majcher, Ting Fung Chung, Yong P. Chen, Igor Jovanovic

Birck and NCN Publications

Graphene field effect transistors (GFETs) fabricated by chemical vapor deposition graphene deposited onto SiC substrates exhibit sensitivity to broadband visible light. The hysteretic nature of this GFET type was studied utilizing a new current-voltage measurement technique in conjunction with current-time measurements. This measurement method accounts for hysteretic changes in graphene response and enables transfer measurements that can be attributed to fixed gate voltages. Graphene hysteresis is shown to be consistent with electrochemical p-type doping, and current-time measurements clearly resolve a hole to electron to hole carrier transition in graphene with a single large change in gate voltage. (C) 2013 AIP …

Surface Morphology Evolution Of M-Plane (1(1)Over-Bar00) Gan During Molecular Beam Epitaxy Growth: Impact Of Ga/N Ratio, Miscut Direction, And Growth Temperature, Jiayi Shao, Liang Tang, Colin Edmunds, Geoff C. Gardner, Oana Malis, Michael J. Manfra

Birck and NCN Publications

We present a systematic study of morphology evolution of [1 (1) over bar 00] m-plane GaN grown by plasma-assisted molecular beam epitaxy on free-standing m-plane substrates with small miscut angles towards the -c [000 (1) over bar] and +c [0001] directions under various gallium to nitrogen (Ga/N) ratios at substrate temperatures T = 720 degrees C and T = 740 degrees C. The miscut direction, Ga/N ratio, and growth temperature are all shown to have a dramatic impact on morphology. The observed dependence on miscut direction supports the notion of strong anisotropy in the gallium adatom diffusion barrier and growth …

Silicon Quantum Electronics, Floris A. Zwanenburg, Andrew S. Dzurak, Andrea Morello, Michelle Y. Simmons, Lloyd C. L. Hollenberg, Gerhard Klimeck, Sven Rogge, Susan N. Coppersmith, Mark A. Eriksson

Birck and NCN Publications

This review describes recent groundbreaking results in Si, Si/SiGe, and dopant-based quantum dots, and it highlights the remarkable advances in Si-based quantum physics that have occurred in the past few years. This progress has been possible thanks to materials development of Si quantum devices, and the physical understanding of quantum effects in silicon. Recent critical steps include the isolation of single electrons, the observation of spin blockade, and single-shot readout of individual electron spins in both dopants and gated quantum dots in Si. Each of these results has come with physics that was not anticipated from previous work in other …

Quest For Organic Plasmonics, Lei Gu, J. Livenere, G. Zhu, Evgenii E. Narimanov, M. A. Noginov

Birck and NCN Publications

Many photonic metamaterials and plasmonic devices, in spite of their unparalleled responses to light waves and nearly fantastic applications, suffer from absorption loss in constituent metallic components. Unfortunately, none of the known techniques aimed to conquer the absorption loss has led to a revolutionary technological breakthrough, prompting a continuing quest for efficient solutions to the loss problem. In this letter, we study optical properties of non-metallic organic plasmonic and epsilon-near-zero materials and demonstrate propagation of a surface plasmon polariton at the interface between solid organic dye and air. (C) 2013 AIP Publishing LLC.

High Precision Dynamic Alignment And Gap Control For Optical Near-Field Nanolithography, Xiaolei Wen, Luis M. Traverso, Pornsak Srisungsitthisunti, Xianfan Xu, Euclid E. Moon

Birck and NCN Publications

The authors demonstrate the use of interferometric-spatial-phase-imaging (ISPI) to control a gap distance of the order of nanometers for parallel optical near-field nanolithography. In optical near-field nanolithography, the distance between the optical mask and the substrate needs to be controlled within tens of nanometers or less. The ISPI technique creates interference fringes from checkerboard gratings fabricated on the optical mask, which are used to determine the gap distance between the mask and the substrate surfaces. The sensitive of this gapping technique can reach 0.15 nm. With the use of ISPI and a dynamic feedback control system, the authors can precisely …

Electrochemical Nanofabrication Using Polyacrylamide Hydrogel As Soft Stamps, Wen Sun, Hai-Tao Fan, Da-Xiao Zhang, Dong-Jie Hu, Yong-Liang Zhou

Journal of Electrochemistry

The fabrication resolution of electrochemical wet stamping (E-WETS) was enhanced to several hundred nanometers from several ten micrometers by using polycarylamide gel (PAG) as soft stamps and through optimized processes. The PAG stamp was cured on a nanopatterned soft mold and soaked with 0.2 mol·L^-1 KCl solution, then contacted with a silicon wafer with gold film and applied with electric field. And the gold nanopatterns were achieved by the selective anodic dissolving, the diameter of fabricated gold spot was around 200 nm. The parameters which affected the fabrication processes have been discussed in detail.

Optimization Of Electroless Silver Plating Process On Fabric Surface Without Activation And Sensitization, Bo Lian Wang, Ya Ping Zhao, Zai Sheng Cai

Journal of Electrochemistry

Silver was deposited homogeneously on the surface of polyamide fabric by electroless plating without activation and sensitization. The electroless silver plating process was optimized with the orthogonal array testing strategy. It is found that the optimum conditions are the electroless plating time of 50 min with the concentrations of silver nitrate, sodium hydroxide and ammonium hydroxide being 14 g·L^-1, 6 g·L-1 and 130 mL·L^-1, respectively. The surface morphologies, compositions, and phases of fabric samples were characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry (SEM-EDS), X-ray diffraction (XRD). The wear-resisting property was tested by friction fastness …