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Articles 121 - 150 of 334

Full-Text Articles in Nanotechnology Fabrication

Technique Design Of Filter On Surface-Acoustic Waves, Dilmurod Abdujalilovich Davronbekov, Zafar Tulyaganovich Khakimov Dec 2020

Technique Design Of Filter On Surface-Acoustic Waves, Dilmurod Abdujalilovich Davronbekov, Zafar Tulyaganovich Khakimov

Acta of Turin Polytechnic University in Tashkent

The article describes the design of filters on surface acoustic waves (SAWs), which are selective elements and are widely used in blocks, devices and signal processing systems in telecommunications, including wireless communication systems such as cellular, trunking and others. Designs of filters for surfactants are considered, which are divided into two large groups - by functional purpose and by a systematic approach to the synthesis of performance characteristics of filters for surfactants. Optimization algorithms and methods for synthesizing surfactant filters have been developed and improved. An improved technique for the synthesis of a filter based on surface acoustic waves is …


Development And Characterization Of Metal Contacts For Graded Composition Ingan Solar Cells, Reem E. Alhelais Dec 2020

Development And Characterization Of Metal Contacts For Graded Composition Ingan Solar Cells, Reem E. Alhelais

Graduate Theses and Dissertations

There is an increasing demand for high-power electronic components and optoelectronic devices with low-loss and high efficiency. III-nitride semiconductor materials have demonstrated great potential for high-power, high-frequency, and high-temperature applications because of their remarkable and wide-ranging electronic and physical properties. These material systems, including alloys of AlN, GaN, and InN, are currently being explored for their potential to develop efficient photovoltaic cells. They can potentially achieve higher efficiency because of their very high direct wide band edge, absorption coefficients, and resistance to defects. The compositionally graded Group III-nitride alloy allows access to a large range of energies by varying the …


Fabrication And Application Of Flexible Sensors, Tallis Huther Da Costa Aug 2020

Fabrication And Application Of Flexible Sensors, Tallis Huther Da Costa

LSU Doctoral Dissertations

A transfer printing method was developed to transfer carbon nanotubes (CNTs) from polyethylene terephthalate (PET) film to poly(dimethyl siloxane) (PDMS) polymer. Carbon nanotubes are composed of carbon atoms arranged in a honeycomb lattice structure, which are electrically conducting. When embedded in a nonconducting polymer, carbon nanotubes impart electrical conductivity to the nanocomposite, thus forming a nanocomposite that has potential applications in highly sensitive strain and pressure sensors. Several printing methods have been studied to deposit carbon nanotubes onto PDMS, including inkjet printing. Inkjet printing is a desirable deposition method since it is low-cost, simple, and allows the processing of aqueous-based …


Nonlinear Nanophotonic Devices In The Ultraviolet To Visible Wavelength Range, Jinghan He, Hong Chen, Jin Hu, Jingan Zhou, Yingmu Zhang, Andre Kovach, Constantine Sideris, Mark C. Harrison, Yuji Zhao, Andrea M. Armani Jul 2020

Nonlinear Nanophotonic Devices In The Ultraviolet To Visible Wavelength Range, Jinghan He, Hong Chen, Jin Hu, Jingan Zhou, Yingmu Zhang, Andre Kovach, Constantine Sideris, Mark C. Harrison, Yuji Zhao, Andrea M. Armani

Engineering Faculty Articles and Research

Although the first lasers invented operated in the visible, the first on-chip devices were optimized for near-infrared (IR) performance driven by demand in telecommunications. However, as the applications of integrated photonics has broadened, the wavelength demand has as well, and we are now returning to the visible (Vis) and pushing into the ultraviolet (UV). This shift has required innovations in device design and in materials as well as leveraging nonlinear behavior to reach these wavelengths. This review discusses the key nonlinear phenomena that can be used as well as presents several emerging material systems and devices that have reached the …


Flexible Capacitive Pressure Sensors And Triboelectric Energy Harvesters Using Laser-Assisted Patterning Process For Flexible Hybrid Electronic Applications, Valliammai Palaniappan Jul 2020

Flexible Capacitive Pressure Sensors And Triboelectric Energy Harvesters Using Laser-Assisted Patterning Process For Flexible Hybrid Electronic Applications, Valliammai Palaniappan

Masters Theses

This work focuses on the design, fabrication and characterization of novel flexible capacitive pressure sensors and triboelectric energy harvesters using laser-assisted patterning process for flexible hybrid electronic applications. Initially, the capacitive pressure sensor was developed by fabricating a set of polydimethylsiloxanes (PDMS) dielectric films with pyramid shaped micro-structures using a laser-assisted patterning process. The pressure sensor consists of two electrodes (top and bottom) that were fabricated by depositing silver (Ag) on flexible polyethylene terephthalate (PET) using additive screen-printing process. Finally, the pressure sensor was assembled by attaching the top and bottom Ag electrodes to the smooth side of pyramid shaped …


Microrobots For Wafer Scale Microfactory: Design Fabrication Integration And Control., Ruoshi Zhang May 2020

Microrobots For Wafer Scale Microfactory: Design Fabrication Integration And Control., Ruoshi Zhang

Electronic Theses and Dissertations

Future assembly technologies will involve higher automation levels, in order to satisfy increased micro scale or nano scale precision requirements. Traditionally, assembly using a top-down robotic approach has been well-studied and applied to micro-electronics and MEMS industries, but less so in nanotechnology. With the bloom of nanotechnology ever since the 1990s, newly designed products with new materials, coatings and nanoparticles are gradually entering everyone’s life, while the industry has grown into a billion-dollar volume worldwide. Traditionally, nanotechnology products are assembled using bottom-up methods, such as self-assembly, rather than with top-down robotic assembly. This is due to considerations of volume handling …


Design Of Submicron Structured Guided-Mode-Resonance Near-Infrared Polarizer, Marzia Zaman May 2020

Design Of Submicron Structured Guided-Mode-Resonance Near-Infrared Polarizer, Marzia Zaman

Graduate Theses and Dissertations

The objective of this research is to design a larger submicron linear polarizer in the near-infrared wavelength range with a wide bandwidth which can be fabricated using the conventional thin-film microfabrication technology to reduce cost. For this purpose, a gold (Au) wire-grid transmission-type transverse-magnetic (TM) polarizer and a silicon (Si) wire-grid reflection-type TM polarizer, were designed using the guided-mode-resonance filter. The Au wire-grid TM polarizer of 700nm grating width and 1200nm grating period has 95% transmittance at 2400nm, more than 1000nm resonance peak bandwidth, and an extinction ratio (ER) of around 300 with a moderated level of sidebands. The 700nm …


Pool Boiling Inversion On Femtosecond Laser Surface Processed 304 Stainless Steel And Its Impact On Steady-State Time Constants, Justin Costa-Greger, Alfred Tsubaki, Josh Gerdes, Mark Anderson, Craig Zuhlke, Dennis Alexander, Jeff Shield, George Gogos Apr 2020

Pool Boiling Inversion On Femtosecond Laser Surface Processed 304 Stainless Steel And Its Impact On Steady-State Time Constants, Justin Costa-Greger, Alfred Tsubaki, Josh Gerdes, Mark Anderson, Craig Zuhlke, Dennis Alexander, Jeff Shield, George Gogos

UCARE: Research Products

FLSP surfaces resulting in boiling inversion require longer times to reach steady-state once inversion has occurred Boiling inversion has been shown to be the result of changing nucleation dynamics in which a large number of nucleation sites activate Increased time required to reach steady-state is linked to the rate at which these nucleation sites activate. Heat fluxes above the boiling inversion point can require up to an additional 3 hours to reach steady-state, compared to the typical 15-20 minutes reported in the literature


Design Of An Affordable Rotating Drum Electrospinner For Classroom Education, Peder Solberg Mar 2020

Design Of An Affordable Rotating Drum Electrospinner For Classroom Education, Peder Solberg

The Journal of Undergraduate Research

Electrospinning is a technology used to generate small fibers down to nano-scale size. This method of fiber creation has been around for many years. However, in recent years electrospinning has found increased applications, especially in the area of tissue engineering due to its ability to create fibers with properties similar to the extracellular matrix in tissue. An electrospinning platform can illustrate concepts of engineering, electro-mechanical system design, manufacturing, and biomedical applications in one single package. Hence, it provides an excellent opportunity to integrate into secondary (middle and high school) and post-secondary (undergraduate) technology education.

Furthermore, just as integration of 3D …


Evaluation Of Capacitive Deionization Desalination Technology For Irrigation, Ziad Khalifa, Moustafa Elshafei Prof, Abdalrahman Amer, Eng, Ashraf Seleym Dr, Tamer Samir Eng Feb 2020

Evaluation Of Capacitive Deionization Desalination Technology For Irrigation, Ziad Khalifa, Moustafa Elshafei Prof, Abdalrahman Amer, Eng, Ashraf Seleym Dr, Tamer Samir Eng

Chemical Engineering

Desalination of brackish groundwater has great potential to alleviate the problem of the limited water resources in Egypt. In this paper, we studied the desalination of brackish water for irrigation purposes using capacitive deionization (CDI) technology. We investigated a modular unit for use in greenhouses (GH). A GH for the production of tomato requires about 3.2 m3/d of water. The target CDI unit has a production capacity of 32 m3/d for irrigation of 10 greenhouses from brackish water. The paper provides an extensive simulation study to illustrate the influence of various design parameters and to unveil the CDI technology pros …


Electric Field Control Of Fixed Magnetic Skyrmions For Energy Efficient Nanomagnetic Memory, Dhritiman Bhattacharya Jan 2020

Electric Field Control Of Fixed Magnetic Skyrmions For Energy Efficient Nanomagnetic Memory, Dhritiman Bhattacharya

Theses and Dissertations

To meet the ever-growing demand of faster and smaller computers, increasing number of transistors are needed in the same chip area. Unfortunately, Silicon based transistors have almost reached their miniaturization limits mainly due to excessive heat generation. Nanomagnetic devices are one of the most promising alternatives of CMOS. In nanomagnetic devices, electron spin, instead of charge, is the information carrier. Hence, these devices are non-volatile: information can be stored in these devices without needing any external power which could enable computing architectures beyond traditional von-Neumann computing. Additionally, these devices are also expected to be more energy efficient than CMOS devices …


Nanostructured Device Designs For Enhanced Performance In Cds/Cu2S Heterojunction Solar Cells, Benjamin Wells Jan 2020

Nanostructured Device Designs For Enhanced Performance In Cds/Cu2S Heterojunction Solar Cells, Benjamin Wells

Theses and Dissertations--Electrical and Computer Engineering

Nanostructured CdS/Cu2S devices have been simulated using SCAPS-1D to demonstrate enhanced performance over traditional planar device structures. Two designs were examined: a nanowire CdS/planar Cu2S device and a nanowire CdS/nanowire Cu2S device. The addition of nanowires to a device had been previously demonstrated to improve device performance in a nanowire CdS/planar CdTe device by decreasing the amount of light absorbed by the CdS window layer, thus allowing more light to reach the absorber layer. Additionally, the total number of interface states can be greatly reduced due to the decreased total surface area between the window and absorber layers. The nanowire …


Investigation Of Host Nanotube Parameters For Enhancing The Performance Of Nanostructured Cds-Cdte Solar Cells, Deepak Kumar Jan 2020

Investigation Of Host Nanotube Parameters For Enhancing The Performance Of Nanostructured Cds-Cdte Solar Cells, Deepak Kumar

Theses and Dissertations--Electrical and Computer Engineering

Numerical simulations are performed to investigate the effects of host nanotube parameters (pore diameter and pitch for different CdS coverages) and CdTe doping density on device performance in nanowire CdS/ CdTe solar cells using SCAPS-1D. This research finds the optimum values for these parameters in order to achieve the highest efficiency. Experimentally the effect of anodization voltage and fluoride ion concentration on the pore diameter and the pitch are studied for the Titania nanotubes host. It is observed that in the range of 0.3 mL to 2 mL of ammonium fluoride content, pore diameter and the pitch of the Titania …


Rapid Prototyping Of Nanostructures With Electron Beam Induced Processing, Samaneh Esfandiarpour Jan 2020

Rapid Prototyping Of Nanostructures With Electron Beam Induced Processing, Samaneh Esfandiarpour

Theses and Dissertations--Electrical and Computer Engineering

Focused electron beam induced processing (FEBIP) is a nano-scale fabrication technique that allows the direct deposition of functional materials. However, it suffers from significant drawbacks, such as high cost, low speed, unavailable precursors for many materials and low purity of deposits. Liquid-phase focused electron beam induced processes (LP-FEBIP) are being investigated due to the potential benefits over the gas phase technique. In this method, deposition or etching occurs at the interface between a substrate and a bulk liquid. In this work, electron beam induced deposition of copper nanostructures from aqueous solutions of copper sulfate is demonstrated. The addition of sulfuric …


Selective Electron Beam Etching Of Materials Using Liquid Reactants, Sarah Lami Jan 2020

Selective Electron Beam Etching Of Materials Using Liquid Reactants, Sarah Lami

Theses and Dissertations--Electrical and Computer Engineering

Selective Electron Beam Etching of Materials Using Liquid Reactants Nanoscience and nanotechnology require advances in processing, patterning, and characterization of materials to overcome current limitations and generate new de-vices. Electron and ion beam-based processes are vital for fabrication and nano-scale prototyping with significant applications in nanoscale electronic, photonic, and magnetic devices; integrated circuit debugging; and lithographic mask and imprint template repair.

Focused ion and electron beams are routinely used to locally add (printing) or sub-tract (machining) materials. This type of material processing is becoming increasingly important to the integrated circuit manufacturing industry for editing and debug applications. Most significantly, as …


Mems Biosensor For Water-Immersed Application, Kun-Lin Lee Jan 2020

Mems Biosensor For Water-Immersed Application, Kun-Lin Lee

Dissertations and Theses

Although many air-based sensing mechanisms exist, not all of them can be applied in the water-based environment. In order to obtain a cell-based biosensor, the sensing method needs to be reliable and repeatable in a liquid environment. Therefore, this study is focused on transforming existing air-based sensors to water-immersed applications. This study includes two types of sensors.

First, commercial quartz resonators are used to investigate live-cell activity in water-based toxic solutions. I perform toxicity tests using quartz crystal microbalance (QCM). The QCM used in the study has a resonant frequency of 10 MHz and consists of an AT-cut quartz crystal …


Parametric Optimization Of Visible Wavelength Gold Lattice Geometries For Improved Plasmon-Enhanced Fluorescence Spectroscopy, Casey A. Norville Jan 2020

Parametric Optimization Of Visible Wavelength Gold Lattice Geometries For Improved Plasmon-Enhanced Fluorescence Spectroscopy, Casey A. Norville

Graduate Theses, Dissertations, and Problem Reports (ETD)

The exploitation of spectro-plasmonics will allow for innovations in optical instrumentation development and the realization of more efficient optical biodetection components. Biosensors have been shown to improve the overall quality of life through real-time detection of various antibody-antigen reactions, biomarkers, infectious diseases, pathogens, toxins, viruses, etc. has led to increased interest in the research and development of these devices. Further advancements in modern biosensor development will be realized through novel electrochemical, electromechanical, bioelectrical, and/or optical transduction methods aimed at reducing the size, cost, and limit of detection (LOD) of these sensor systems. One such method of optical transduction involves the …


Optical Spectroscopy And Theoretical Modelling Of Carrier Dynamics In Group-Iv Alloy Quantum Dots, Rahnuma Rahman Jan 2020

Optical Spectroscopy And Theoretical Modelling Of Carrier Dynamics In Group-Iv Alloy Quantum Dots, Rahnuma Rahman

Theses and Dissertations

In recent years, Ge1−xSnx alloy quantum dots (QDs) have attracted significant interest due to their potential applications in photodetectors and light emitting devices in visible to mid IR spectral range and compatibility with silicon based platforms. While bulk Ge is an indirect bandgap semiconductor (0.66 eV), direct transitions can be made possible by incorporation of α-Sn at concentrations of ~10%, which however lowers the bandgap. Utilizing quantum confinement by reducing the size to below the Bohr radius also promotes direct transitions and more importantly increases the fundamental transition energies in GeSn alloy QDs, making them suitable for …


Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves Jan 2020

Synthesis Of Graphene Using Plasma Etching And Atmospheric Pressure Annealing: Process And Sensor Development, Andrew Robert Graves

Graduate Theses, Dissertations, and Problem Reports (ETD)

Having been theorized in 1947, it was not until 2004 that graphene was first isolated. In the years since its isolation, graphene has been the subject of intense, world-wide study due to its incredibly diverse array of useful properties. Even though many billions of dollars have been spent on its development, graphene has yet to break out of the laboratory and penetrate mainstream industrial applications markets. This is because graphene faces a ‘grand challenge.’ Simply put, there is currently no method of manufacturing high-quality graphene on the industrial scale. This grand challenge looms particularly large for electronic applications where the …


Interfacial Contact With Noble Metal - Noble Metal And Noble Metal - 2d Semiconductor Nanostructures Enhance Optical Activity, Ricardo Raphael Lopez Romo Dec 2019

Interfacial Contact With Noble Metal - Noble Metal And Noble Metal - 2d Semiconductor Nanostructures Enhance Optical Activity, Ricardo Raphael Lopez Romo

Graduate Theses and Dissertations

Noble metal nanoparticles and two-dimensional (2D) transition metal dichalcogenide (TMD) crystals offer unique optical and electronic properties that include strong exciton binding, spin-orbital coupling, and localized surface plasmon resonance. Controlling these properties at high spatiotemporal resolution can support emerging optoelectronic coupling and enhanced optical features. Excitation dynamics of these optical properties on physicochemically bonded mono- and few-layer TMD crystals with metal nanocrystals and two overlapping spherical metal nanocrystals were examined by concurrently (i) DDA simulations and (ii) far-field optical transmission UV-vis spectroscopic measurements. Initially, a novel and scalable method to unsettle van der Waals bonds in bulk TMDs to prepare …


Exploring Convergence Of Snake Skin-Inspired Texture Designs And Additive Manufacturing For Mechanical Traction, Catherine Sue Tiner Dec 2019

Exploring Convergence Of Snake Skin-Inspired Texture Designs And Additive Manufacturing For Mechanical Traction, Catherine Sue Tiner

Graduate Theses and Dissertations

This research focuses on the understanding, development, and additive manufacture of a 3D printed snake skin-inspired texture pattern. The design functionalities of snake skin were determined through the study of the snake species Python Regius otherwise known as the ball python. Each scale of a snake has hierarchical texture with hexagonal macro-patterns aligned on the ventral surface of the skin with overriding anisotropic micro textured patterns such as denticulations and fibrils. Using a laser-powder bed fusion (L-PBF) process, 420 stainless steel samples were 3D printed which closely resemble the above described directional texture of natural snake skin. This printed surface …


Optical Angular Scatterometry: In-Line Approach For Roll-2-Roll And Nano-Imprint Fabrication Systems, Juan Jose Faria-Briceno Nov 2019

Optical Angular Scatterometry: In-Line Approach For Roll-2-Roll And Nano-Imprint Fabrication Systems, Juan Jose Faria-Briceno

Electrical and Computer Engineering ETDs

As critical dimensions continue to shrink and structures become more complex, metrology processes are challenging to implement during in-line nanomanufacturing. Non-destructive, non-contact, and high-speed conditions are required to achieve proper metrology processes during in-line manufacturing. Optical scatterometry is a nanoscale metrology tool widely used in integrated circuit manufacturing for characterization and quality control. However, most applications of optical scatterometry operate off-line. A high-speed, in-line, non-contact, non-destructive scatterometry angular system has been demonstrated in this work to scan pattern surfaces during real-time nano-fabrication.

Our system has demonstrated scanning capabilities using flat, 1D and 2D complex structures. The flat surface samples consist …


Investigating Nano-Coated Surfaces In Improvement Wear Resistance Of Tillage Tools, Saeed Mehrang Marani, Gholamhossein Shahgholi, Saeed Kanoon Marani Oct 2019

Investigating Nano-Coated Surfaces In Improvement Wear Resistance Of Tillage Tools, Saeed Mehrang Marani, Gholamhossein Shahgholi, Saeed Kanoon Marani

Emirates Journal for Engineering Research

The blade in the tillage operation has the most interaction with soil particles. It causes the wear and tear of this piece and reduces its expected life span. Tillage tool wear is of great importance to farmers in terms of economic aspects, reduced quality tillage operations, and increased power consumption. The aim of this study is to investigate wearing of five materials including st37 steel (SST37) plate, galvanized steel (GAS), and fiberglass (GFRP), and two coatings (i.e., titanium nano-nitride (nano-TiN) and tantalum carbide (nano-TaC)) by sputtering in the plasma medium of the layer based on conventional steel. These pieces were …


Investigation Of The Electrode Polarization Effect For Biosensor Applications, Anil Koklu Aug 2019

Investigation Of The Electrode Polarization Effect For Biosensor Applications, Anil Koklu

Mechanical Engineering Research Theses and Dissertations

My research focuses on electrokinetic transport. Particularly, in this dissertation, we focus on fabrication and testing of micro electrodes with nanostructured surfaces to minimize the electrode polarization (EP) effects for biosensor applications. In the first study, electrochemical deposition of gold nanoparticles on to planar gold electrodes was used to generate rough surfaces. Dendritic nanostructures that reduced EP up to two orders of magnitude was obtained by optimizing the deposition conditions. These structures also enhanced dielectrophoresis (DEP) response of our bio-chips, making them usable in physiological buffers. In further studies we discovered a universal scaling of EP in the frequency domain, …


Smart Charging Of Future Electric Vehicles Using Roadway Infrastructure, Sara Ahmed, Ethan Ahn, Mahmoud Reda Taha, Samer Dessouky, Moneeb Genedy, Daniel Fernandez, Ann Sebestian, Patience Raby Aug 2019

Smart Charging Of Future Electric Vehicles Using Roadway Infrastructure, Sara Ahmed, Ethan Ahn, Mahmoud Reda Taha, Samer Dessouky, Moneeb Genedy, Daniel Fernandez, Ann Sebestian, Patience Raby

Data

Corresponding data set for Tran-SET Project No. 18ITSTSA03. Abstract of the final report is stated below for reference:

"Inspired by the fact that there is an immense amount of renewable energy sources available on the roadways such as mechanical pressure and frictional heat, this study presented the development and implementation of an innovative charging technique for future electric vehicles (EVs) by fully utilizing the existing roadways and the state-of-the-art nanotechnology and power electronics. The project introduced a novel wireless charging system, SIC (Smart Illuminative Charging), that uses LEDs powered by piezoelectric nanomaterials as the energy transmitter source and thin film …


Toolpath Planning Methodology For Multi-Gantry Fused Filament Fabrication 3d Printing, Hieu Trung Bui Aug 2019

Toolpath Planning Methodology For Multi-Gantry Fused Filament Fabrication 3d Printing, Hieu Trung Bui

Graduate Theses and Dissertations

Additive manufacturing (AM) has revolutionized the way industries manufacture and prototype products. Fused filament fabrication (FFF) is one of the most popular processes in AM as it is inexpensive, requires low maintenance, and has high material utilization. However, the biggest drawback that prevents FFF printing from being widely implemented in large-scale production is the cycle time. The most practical approach is to allow multiple collaborating printheads to work simultaneously on different parts of the same object. However, little research has been introduced to support the aforementioned approach. Hence a new toolpath planning methodology is proposed in this paper. The objectives …


Solarpede: An Untethered Micro Robot Powered By Light., Jordan Fredrick Klotz Aug 2019

Solarpede: An Untethered Micro Robot Powered By Light., Jordan Fredrick Klotz

Electronic Theses and Dissertations

Micro-Robotics looks to implement robotics principles at a small scale and has gained popularity in recent decades as a gateway to new research areas such as micro-factory applications. The SolarPede is a second-generation, cm-scale micro-crawler designed for such micro factory applications which is equipped with a legged locomotion system and an electronic backpack. The SolarPede is an evolution of its predecessors and features power and signal conditioning capabilities, gait pattern generation, and Bluetooth connectivity. The components which make up SolarPede have been full validated and tested, and its systems have been realized in the form of a body made from …


Pixelated Gasb Membranes For Photovoltaics: Fabrication And Structure-Property Relationships, Vijay Saradhi Mangu Jul 2019

Pixelated Gasb Membranes For Photovoltaics: Fabrication And Structure-Property Relationships, Vijay Saradhi Mangu

Electrical and Computer Engineering ETDs

In this thesis, I present a reliable and efficient approach to heterogeneous integration of single-crystalline GaSb semiconductors with highly mismatched materials. The mismatch may refer to the crystalline structure and the thermal expansion coefficient of single-crystalline GaSb and the other materials of interest. The strategy of hetero-integration relies on epitaxial lift-off. This approach prevents the formation of extended structural defects that are detrimental to the performance of optoelectronic devices and preserves GaSb growth substrates for potential reuse.

Within my research work, I have overcome some outstanding challenges of epitaxial lift-off of GaSb, and I have demonstrated the operation of single-crystalline …


Silica-Coated Metallic Nanoparticle-Based Hierarchical Super-Hydrophobic Surfaces Fabricated By Spin-Coating And Inverse Nanotransfer Printing, Shengjie Zhai, Hui Zhao Jun 2019

Silica-Coated Metallic Nanoparticle-Based Hierarchical Super-Hydrophobic Surfaces Fabricated By Spin-Coating And Inverse Nanotransfer Printing, Shengjie Zhai, Hui Zhao

Mechanical Engineering Faculty Research

By combining spin coating and inverse nanotransfer printing, silica-coated gold nanoparticles are patterned onto polydimethylsiloxane (PDMS) superhydrophobic surfaces to form a hierarchical structure. A layer of nanoparticles is spin-coated on a flat silicon substrate serving as the stamp, which is then transferred to the raised regions of PDMS surfaces. Our inverse nanotransfer printing is in contrast to the standard nanotransfer printing, which transfers metal from the raised regions of a stamp to a flat PDMS surface. The fabricated hierarchical surface exhibits a higher contact angle and delays the Cassie-Wenzel transition during evaporation of a sessile droplet, indicating an improvement of …


Symmetry And Dopant Diffusion In Inverted Nanopyramid Arrays For Thin Crystalline Silicon Solar Cells, Seok Jun Han May 2019

Symmetry And Dopant Diffusion In Inverted Nanopyramid Arrays For Thin Crystalline Silicon Solar Cells, Seok Jun Han

Chemical and Biological Engineering ETDs

In this dissertation, we enhance the efficiency of thin flexible monocrystalline silicon solar cells by breaking symmetry in light trapping nanostructures and improving homogeneity in dopant concentration profile. These thin cells are potentially less expensive than conventional thick silicon cells by using less silicon material and making the cells more convenient to be handled when supported on polymer films. Moreover, these cells are widely applicable due to their flexibility and lightweight. However, for high efficiencies, these cells require effective light trapping and charge collection. We achieve these in cells based on 14-mm-thick free-standing silicon films with light-trapping arrays of nanopyramidal …