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Engineering

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University of Massachusetts Amherst

Doctoral Dissertations

Nanofabrication

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Modeling And Simulation Of Driven Nanopatterning Of Bulk-Material And Thin-Film Surfaces, Ashish Kumar Oct 2019

Modeling And Simulation Of Driven Nanopatterning Of Bulk-Material And Thin-Film Surfaces, Ashish Kumar

Doctoral Dissertations

Material nanostructures such as nanowires, quantum dots, and nanorings have a wide variety of applications in electronic and photonic devices among numerous others. Assembling uniformly arranged and consistently sized nanostructure patterns on solid material surfaces is a major challenge for nanotechnology. This dissertation focuses on developing predictive models capable of simulation and analysis of such nanopattern formation on bulk material and strained thin film surfaces. Single-layer atomic clusters (islands) of sizes larger than a critical size on crystalline conducting substrates undergo morphological instabilities when driven by an externally applied electric field or thermal gradient. We have conducted a systematic and …


Fabrication Of High Refractive Index, Periodic, Composite Nanostructures For Photonic And Sensing Applications, Irene Howell Nov 2018

Fabrication Of High Refractive Index, Periodic, Composite Nanostructures For Photonic And Sensing Applications, Irene Howell

Doctoral Dissertations

This dissertation examines methods of fabricating high refractive index, periodic structures and their applications. Structures with a refractive index periodicity in one-dimensionally are fabricated by stacking layers of (high-refractive index) nanoparticle-filled and unfilled layers. More complex two- and three-dimensional structures are fabricated by direct printing of nanoparticles via solvent-assisted soft nanoimprint lithography. Polymer-nanoparticle composites are an active area of research and development especially for photonic applications. We show use of two composite formulations, first for fabrication of one-dimensional photonic crystals, and second for scalable UV-nanoimprinting. One dimensional photonic crystals, which possess a periodicity in refractive index, result in a constructive …


Memristive Nanodevices And Arrays: Scaling And Novel Applications, Shuang Pi Mar 2018

Memristive Nanodevices And Arrays: Scaling And Novel Applications, Shuang Pi

Doctoral Dissertations

This dissertation addresses the challenges for device scaling and novel application of nanoscale memristive devices and device arrays through demonstrating the first working sub-10 nm memristor array, the first ultra-dense atomic scale working memristor array and the first high performance nanoscale radiofrequency switch based on memristive devices. Nanoimprint lithography is used to generate the sub-10 nm cross-point memristor array. The imprint mold with sub-10 nm features is generated by using wet chemical method to shrink the larger features on a master mold. The imprinting, pattern transfer and metallization process are closely monitored to enforce optimal conditions for sub-1 nm critical …


Three-Dimensional Memristor Integrated Circuits And Applications, Peng Lin Nov 2017

Three-Dimensional Memristor Integrated Circuits And Applications, Peng Lin

Doctoral Dissertations

New computing paradigms are highly demanded in the “Big Data” era to efficiently process, store and extract useful information from overwhelmingly rich amount of data. New computing systems based on large scale memristor circuits emerges as a very promising candidate due to its capability to both store and process information, thus eliminating the von Neumann bottleneck in the conventional complementary metal oxide semiconductor (CMOS) based computers. As the lateral scaling of the device geometry approaching its physical limit, three-dimensional stacking of multiple device layers becomes necessary to further increase the packing density. Moreover, innovations in the 3D circuits design can …


Terahertz Radiation From Electrically Driven Graphene, Single Walled Carbon Nanotubes, And Platinum Nanostructures, Martin M. Muthee Nov 2016

Terahertz Radiation From Electrically Driven Graphene, Single Walled Carbon Nanotubes, And Platinum Nanostructures, Martin M. Muthee

Doctoral Dissertations

Terahertz power generation continues to be a subject of great interest owing mainly to the sparsity and diversity of sources. Though there has been remarkable development in sources, ranging from quantum cascade lasers, time domain spectroscopy systems and multiplier sources, there still exists hurdles when it comes to integration and application. While some sources excel in a particular attribute like power, they are severely limited when it comes to on-chip or system integration, for example. Furthermore, tunable bandwidth and power are inversely related. Electrically driven radiation sources are emergent and this thesis presents work in terahertz generation from arrays of …