Nanotechnology Commons^™

Monte Carlo Modeling Of Spin Polarized Photoemission From Gaas At Low Temperatures And Positive Electron Affinity Surfaces, John Rison Callahan

Graduate Research Theses & Dissertations

Research and development of new photocathode materials are essential to the continuing success and productivity of accelerator technology. High-quality photocathodes characterized by high quantum efficiencies, long lifetimes, low mean transverse energies, and robustness to vacuum environments and operation loads are becoming increasingly essential to the successful operation of the next generation of high brightness accelerator applications. For nuclear and high-energy physics experiments and other applications that rely on spin-polarized electron beams, photocathodes must also demonstrate high electron spin polarizations. The development of state of-the-art spin-polarized photocathodes will require both development of methods to improve the quality of already existing cathode …

Coulomb Blockade-Mediated Field Emission Sources Using Ultra-Nanocrystalline Diamond, Jevin Jensen

Graduate Research Theses & Dissertations

Coulomb Blockade effects in field emission provide interesting means of achieving brighter electron sources for numerous applications, ranging from vacuum electronics to the next generation of electron beam technology. Microelectronics cleanroom methods are presented in this thesis for production of field emission sources moderated by the Coulomb Blockade. The use of common processes is an essential step toward widespread experimentation with Coulomb Blockade-mediated field emission apparatuses. The main feature to be explored is the use of nano-diamond films for their potential applicability for this desired outcome. Ultra-Nanocrystalline Diamond is used in two different ways to achieve this, both as a …

Cathode Electron Sources For Cold Field Emission: Fabrication Methodology For Discretely Patterned High Aspect Ratio Silicon Nanotips, Austin Luke Rose

Graduate Research Theses & Dissertations

The development of high aspect ratio electron sources for use in Cold Field Emission (CFE) is an area of research interest with a wide range of potential applications from electron microscopy to CFE X-ray sources for computed tomography in the medical field. The development of cathode electron sources that are capable of electron emission at room temperature is attractive because of their ability to produce bright high current electron beams with less energy spread than their Thermionic or Schottky equivalents. These parameters are impacted by the sharpness of the emitter’s apex, creating the desire for high aspect ratio emitters. Additionally, …

Growth Optimization Of Zinc-Oxide Nanowires/Nanorods Using Hydrothermal Synthesis On Silicon Wafers, Mythili Ananthula

Graduate Research Theses & Dissertations

This research paper aims to grow and optically characterize the Zinc-Oxide (ZnO) nanowires grown using the hydrothermal synthesis method on different semiconductor wafers. We have developed the samples on p-type silicon, n-type silicon, and silicon di-oxide wafers at different temperatures, molarities, and times. Using hydrothermal synthesis method Zinc Oxide nanowires are grown. Zinc Nitrate Hexa-hydrate and Hexamethylenetetramine are chemical components used in the hydrothermal synthesis method at low temperatures.

Different types of analysis have been done on these samples with the help of “Argonne National Laboratory.” The optical absorption spectra were obtained using Perkin Elmer LAMBDA 950 UV-VIS-NIR Spectrophotometer. Photoluminescence …

Shape Tuning Of Silicon Nano-Tip Arrays Through Reactive Ion Etching For Cold Field Emission, Giridhar Tulasi Ram Sankabathula

Graduate Research Theses & Dissertations

Large area silicon nano-tip arrays have been predominantly used as cold cathode electron sources in the wide range of field emission applications. Various fabrication methodologies have been developed over the decades to obtain sharp-pointed field emitters. In this thesis, we mainly emphasized on reproducing high aspect ratio field emitters and to study their surface topographical changes encountered through reactive ion etching. A discrete set of high-density field emitters have been fabricated over the large area surfaces through a three-step nanofabrication process. The surface curvatures of the obtained emitter tips are finely tuned with multiple oxidation cycles to achieve a tip’s …

Multifunctional Nanocomposites In Coating Technology: Synthesis, Characterization, Formulation, Evaluation And Application, Sudeshna Chakraborty

Graduate Research Theses & Dissertations

Application of Nanomaterials using nanotechnology has gained significant

attention in the coating industry in recent years. Their application has had a great

impact, particularly in the 3C industries (computer, communication, and construction).

Incorporation of nanomaterials into polymer carriers through a systematic approach to

coating processes can enhance various physical properties, such as mechanical,

optical, electrical and thermal properties. The current dissertation focused on the

synthesis and characterization of new nanomaterials like mesoporous silica or

nanocomposites like copper-doped zinc oxide that can be used in the coating to study

thermal cooling performance and enhancement of thermal conductivity. New thermal

devices will …

Investigating The Effects Of Orientation Control Of Graphene Nanoplatelet Suspensions By A Magnetic Field On The Viscosity Of A Nanofluid System, Radhika Iyer

Graduate Research Theses & Dissertations

In this investigation, the rheological behavior of paraffin oil containing diamagnetic suspensions is characterized under varying magnetic field conditions. The particles suspended in the white paraffin oil at mass concentrations of 0.1, 0.3, 0.5, 0.7 and 1% m/m are two-dimensional graphene nanoplatelets with an average thickness of 2 – 8 nm. Rheological experiments were conducted using a Brookfield DV2T viscometer with a modified cylindrical spindle over the range of shear rates between 192 s-1 to 1928 s-1. A Neodymium N42 ring magnet with a surface strength of 1.32 T generated the magnetic field conditions for the rheological experiments and was …