Nanotechnology Fabrication Commons^™

Parameters Affecting The Resistivity Of Lp-Ebid Deposited Copper Nanowires, Gabriel Smith

Theses and Dissertations--Electrical and Computer Engineering

Electron Beam Induced Deposition (EBID) is a direct write fabrication process with applications in circuit edit and debug, mask repair, and rapid prototyping. However, it suffers from significant drawbacks, most notably low purity. Work over the last several years has demonstrated that deposition from bulk liquid precursors, rather than organometallic gaseous precursors, results in high purity deposits of low resistivity (LPEBID). In this work, it is shown that the deposits resulting from LP-EBID are only highly conductive when deposited at line doses below 25μC/cm. When the dose exceeds this value, the resulting structure is highly porous providing a poor conductive …

Fabrication And Characterization Of Organic-Inorganic Hybrid Perovskite Solar Cells, Hojjatollah Sarvari

Theses and Dissertations--Electrical and Computer Engineering

Solar energy as the most abundant source of energy is clean, non-pollutant, and completely renewable, which provides energy security, independence, and reliability. Organic-inorganic hybrid perovskite solar cells (PSCs) revolutionized the photovoltaics field not only by showing high efficiency of above 22% in just a few years but also by providing cheap and facile fabrication methods.

In this dissertation, fabrication of PSCs in both ambient air conditions and environmentally controlled N₂-filled glove-box are studied. Several characterization methods such as SEM, XRD, EDS, Profilometry, four-point probe measurement, EQE, and current-voltage measurements were employed to examine the quality of thin films …

Modeling Of Thermally Aware Carbon Nanotube And Graphene Based Post Cmos Vlsi Interconnect, K M Mohsin

LSU Doctoral Dissertations

This work studies various emerging reduced dimensional materials for very large-scale integration (VLSI) interconnects. The prime motivation of this work is to find an alternative to the existing Cu-based interconnect for post-CMOS technology nodes with an emphasis on thermal stability. Starting from the material modeling, this work includes material characterization, exploration of electronic properties, vibrational properties and to analyze performance as a VLSI interconnect. Using state of the art density functional theories (DFT) one-dimensional and two-dimensional materials were designed for exploring their electronic structures, transport properties and their circuit behaviors. Primarily carbon nanotube (CNT), graphene and graphene/copper based interconnects were …

Laser-Assisted Metal Organic Chemical Vapor Deposition Of Gallium Nitride, Hossein Rabiee Golgir

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Due to its unique properties, gallium nitride is of great interest in industry applications including optoelectronics (LEDs, diode laser, detector), high power electronics, and RF and wirelss communication devices. The inherent shortcomings of current conventional deposition methods and the ever-increasing demand for gallium nitride urge extended efforts for further enhancement of gallium nitride deposition. The processes of conventional methods for gallium nitride deposition, which rely on thermal heating, are inefficient energy coupling routes to drive gas reactions. A high deposition temperature (1000-1100 °C) is generally required to overcome the energy barriers to precursor adsorption and surface adatom migration. However, there …

Development Of Intermediate Band Solar Cell Through Ingan Quantum Well Structures, Kelly Mckenzie

Electrical Engineering Undergraduate Honors Theses

In the search for high-efficiency solar cells, In_xGa_1-xN has come under scrutiny as a unique material with high potential. This is due to characteristics including an easily tunable bandgap, large range of potential bandgap values, and high heat resistance. However, one factor limiting its adaptation is the high density of crystal defects. In this thesis, the qualities of InGaN are discussed and the intermediate band solar cell structure is introduced. Additionally, the growth and characterization of two sets of InGaN-based solar cell devices are reported and evaluated.

Optimization Of Graphene Parameters For The Development Of Supercapacitors, Jessica L. Montgomery

Mechanical Engineering Undergraduate Honors Theses

In the growing market of evolving electronic devices and the sustainable goals of the energy industry, better sources of energy dense storage devices are needed. Carbon based supercapacitors have attracted the attention of research due to the natural properties of high electrical conductivity, chemical and electrochemical stability, and high surface area. The object of this thesis is to expand upon current knowledge of reduced graphene oxide to better understand the effectiveness of the material as electrode in supercapacitors. This thesis will focus on the physical orientation of supercapacitors to further develop a device that will allow a set of supercapacitors …

Optical Spectroscopy Of Wide Bandgap Semiconductor Heterostructures And Group-Iv Alloy Quantum Dots, Tanner A. Nakagawara

Theses and Dissertations

Efficient and robust blue InGaN multiple quantum well (MQW) light emitters have become ubiquitous; however, they still have unattained theoretical potential. It is widely accepted that “localization” of carriers due to indium fluctuations theoretically enhance their efficiency by moderating defect-associated nonradiative recombination. To help develop a complete understanding of localization effects on carrier dynamics, this thesis explores degree of localization in InGaN MQWs and its dependence on well thickness and number of wells, through temperature and power dependent photoluminescence measurements. Additionally, silicon-compatible, nontoxic, colloidally synthesizable 2-5 nm Ge_1-xSn_x alloy quantum-dots (QDs) are explored for potential visible to …

Low-Temperature Fabrication Process For Integrated High-Aspect Ratio Metal Oxide Nanostructure Semiconductor Gas Sensors, William Paul Clavijo

Theses and Dissertations

This work presents a new low-temperature fabrication process of metal oxide nanostructures that allows high-aspect ratio zinc oxide (ZnO) and titanium dioxide (TiO₂) nanowires and nanotubes to be readily integrated with microelectronic devices for sensor applications. This process relies on a new method of forming a close-packed array of self-assembled high-aspect-ratio nanopores in an anodized aluminum oxide (AAO) template in a thin (2.5 µm) aluminum film deposited on a silicon and lithium niobate substrate (LiNbO₃). This technique is in sharp contrast to traditional free-standing thick film methods and the use of an integrated thin aluminum film …

Strategies And Techniques For Fabricating Mems Bistable Thermal Actuators., Dilan Ratnayake

Electronic Theses and Dissertations

Bistable elements are beginning to appear in the field of MEMS as they allow engineers to design sensors and actuators which require no electrical power and possess mechanical memory. This research focuses on the development of novel strategies and techniques for fabricating MEMS bistable structures to serve as no electrical power thermal actuators. Two parallel strategies were explored for the design and fabrication of the critical bistable element. Both strategies involved an extensive material study on candidate thin film materials to determine their temperature coefficient of expansion and as-deposited internal stress properties. Materials investigated included titanium tungsten, Invar, silicon nitride …

Atomistic Configuration Interaction Simulation Tool For Semiconductor Based Quantum Computing Devices, Jingbo Wu, Archana Tankasala, Jim Fonseca, Rajib Rahman, Gerhard Klimeck

The Summer Undergraduate Research Fellowship (SURF) Symposium

Solid-state devices are promising candidates for quantum computing applications due to obvious advantages in compatibility with semiconductor fabrication technologies and the extremely long coherent times of electron and nuclear spins in these devices. In such devices, electron interactions are crucial for single and two qubit gate operations. Thus it is essential to evaluate these electron-electron interactions accurately for precise qubit control. It is shown that Atomistic Configuration Interaction can be used to accurately determine electron-electron interactions in realistic semiconductor quantum computing devices. In this work, an online simulation tool on Atomistic Configuration Interaction has been implemented and published on nanoHUB.org, …

Electron Beam Induced Deposition Of Highly Conductive Copper Nanowires From Bulk Liquids, Amjad M. Syam

Theses and Dissertations--Electrical and Computer Engineering

Electron-beam induced deposition (EBID) is a position-controlled technique that can directly fabricate nanometer-sized structures in functional materials. In the standard process, a gaseous precursor delivers the desired substance to the substrate for deposition. However, the material purity from these precursors is typically poor, which often negatively affects the functional properties of the deposit. Recently, bulk liquid precursors have been investigated as promising reactants for high purity deposition without the need for post-processing. In this work, EBID from bulk liquids is shown to yield highly conductive nanowire deposits. Aqueous solutions containing copper sulfate (CuSO₄) and sulfuric acid (H_{2 …}

Nanosphere Lithography And Its Application In Rapid And Economic Fabrication Of Plasmonic Hydrogenated Amorphous Silicon Photovoltaic Devices, Chenlong Zhang

Dissertations, Master's Theses and Master's Reports

Solar photovoltaic (PV) devices harvest energy from solar radiation and convert it to electricity. PV technologies, as an alternative to traditional fossil fuels, use clean and renewable energy while minimizing pollution. For decades researchers have been developing thin film solar cells as an important alternatives to the relatively expensive bulk crystal solar cell technology. Among those, hydrogenated amorphous silicon (a-Si:H) solar cells prevails for good efficiency, non-toxic and materially abundant nature. However, a-Si:H thickness must be minimized to prevent light induced degradation, so optical enhancement is necessary. Light manipulation has to be applied and carefully engineered to trap light within …

Electric Field Controlled Strain Induced Switching Of Magnetization Of Galfenol Nanomagnets In Magneto-Electrically Coupled Multiferroic Stack, Hasnain Ahmad

Theses and Dissertations

The ability to control the bi-stable magnetization states of shape anisotropic single domain nanomagnets has enormous potential for spawning non-volatile and energy-efficient computing and signal processing systems. One of the most energy efficient switching methods is to adopt a system of a 2-phase multiferroic nanomagnet, where a voltage applied on the piezoelectric layer generates a strain in it and the strain is elastically transferred to the magnetostrictive nanomagnet which rotates the magnetization states of the nanomagnet at room temperature via the converse magnet-electric effect. Recently, it has been demonstrated that the magnetization of a Co nanomagnet can be switched between …

Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian

Theses and Dissertations

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that …

Optical Investigations Of Ingan Heterostructures And Gesn Nanocrystals For Photonic And Phononic Applications: Light Emitting Diodes And Phonon Cavities, Shopan D. Hafiz

Theses and Dissertations

InGaN heterostructures are at the core of blue light emitting diodes (LEDs) which are the basic building blocks for energy efficient and environment friendly modern white light generating sources. Through quantum confinement and electronic band structure tuning on the opposite end of the spectrum, Ge_1−xSn_x alloys have recently attracted significant interest due to its potential role as a silicon compatible infra-red (IR) optical material for photodetectors and LEDs owing to transition to direct bandgap with increasing Sn. This thesis is dedicated to establishing an understanding of the optical processes and carrier dynamics in InGaN heterostructures for achieving …

Hybrid Straintronics-Spintronics: Energy-Efficient Non-Volatile Devices For Boolean And Non-Boolean Computation, Ayan K. Biswas

Theses and Dissertations

Research in future generation computing is focused on reducing energy dissipation while maintaining the switching speed in a binary operation to continue the current trend of increasing transistor-density according to Moore’s law. Unlike charge-based CMOS technology, spin-based nanomagnetic technology, based on switching bistable magnetization of single domain shape-anisotropic nanomagnets, has the potential to achieve ultralow energy dissipation due to the fact that no charge motion is directly involved in switching. However, switching of magnetization has not been any less dissipative than switching transistors because most magnet switching schemes involve generating a current to produce a magnetic field, or spin transfer …

Skin Effect Suppression In Infrared-Laser Irradiated Planar Multi-Walled Carbon Nanotube/Cu Conductors, Kamran Keramatnejad, Yang Gao, Yunshen Zhou, Hossein Rabiee Glogir, Mengmeng Wang, Yongfeng Lu

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Skin effect suppression in planar multi-walled carbon nanotube (MWCNT)/Copper (Cu) conductors was realized at the 0-10 MHz frequency range through infrared laser irradiation of MWCNTs, which were coated on the surface of the Cu substrate via the electrophoretic deposition (EPD) method. The effect of laser irradiation and its power density on electrical and structural properties of the MWCNT/Cu conductors was investigated using a wavelength-tunable CO2 laser and then comparing the performance of the samples prepared at different conditions with that of pristine Cu. The irradiation at λ=9.219 μm proved to be effective in selective delivery of energy towards depths close …

Simulating Nanowires And Ultra-Thin Body Transistors Using Nemo5 On Nanohub.Org, Liang Yuan Dai, James E. Fonseca, Chu Yuan Chen, Gerhard Klimeck

The Summer Undergraduate Research Fellowship (SURF) Symposium

During the past twenty years, the most important aspects of semiconductor electronics have advanced into the nanometer range, resulting in exponential increases of microprocessor computing performance. As the size of electrical components continues to shrink, the cost of experimental research and industrial fabrication in this field has increased dramatically. Thus, the development of accurate nanoscale model simulations becomes necessary as a measure to decrease the high financial expenses of advancing semiconductor technology. This simulator supports atomistic modeling in order to provide an accurate description of the nanoscale devices, as current electrical components operate in the quantum regime and are affected …

Single-Walled Carbon Nanotube Arrays For High Frequency Applications, Asmaa Elkadi

Graduate Theses and Dissertations

This dissertation presents a thorough analysis of semiconducting Single-Walled Carbon Nanotube-based devices, followed by a test structure fabrication and measurements.

The analysis starts by developing an individual nanotube model, which is then generalized for many nanotubes and adding the parasitic elements. The parasitic elements appear when forming the device electrodes degrade the overall performance.

The continuum model of an individual nanotube is developed. A unique potential function is presented to effectively describe the electron distribution in the carbon nanotube subsequently facilitating solving Schrödinger's equation to obtain the energy levels, and to generalize the model for many nanotubes.

It is shown …

Multiferroic Tunnel Junctions And Ferroelectric Control Of Magnetic State At Interface, Y. W. Yin, M. Raju, W. J. Hu, John D. Burton, Y.-M. Kim, A. Y. Borisevich, S. J. Pennycook, S. M. Yang, T. W. Noh, Alexei Gruverman, X. G. Li, Z. D. Zhang, Evgeny Y. Tsymbal, Qi Li

Alexei Gruverman Publications

As semiconductor devices reach ever smaller dimensions, the challenge of power dissipation and quantum effect place a serious limit on the future device scaling. Recently, a multiferroic tunnel junction (MFTJ) with a ferroelectric barrier sandwiched between two ferromagnetic electrodes has drawn enormous interest due to its potential applications not only in multi-level data storage but also in electric field controlled spintronics and nanoferronics. Here, we present our investigations on four-level resistance states, giant tunneling electroresistance (TER) due to interfacial magnetoelectric coupling, and ferroelectric control of spin polarized tunneling in MFTJs. Coexistence of large tunneling magnetoresistance and TER has been observed …

Trapping Light With Nanostructures For Sensors, Kareem Garriga

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Nanostructured Semiconductor Device Design In Solar Cells, Hongmei Dang

Theses and Dissertations--Electrical and Computer Engineering

We demonstrate the use of embedded CdS nanowires in improving spectral transmission loss and the low mechanical and electrical robustness of planar CdS window layer and thus enhancing the quantum efficiency and the reliability of the CdS-CdTe solar cells. CdS nanowire window layer enables light transmission gain at 300nm-550nm. A nearly ideal spectral response of quantum efficiency at a wide spectrum range provides an evidence for improving light transmission in the window layer and enhancing absorption and carrier generation in absorber. Nanowire CdS/CdTe solar cells with Cu/graphite/silver paste as back contacts, on SnO₂/ITO-soda lime glass substrates, yield the …

Strain Controlled Ultra-Low-Energy Magnetic Tunneling Junction, Hasnain Ahmad, Supriyo Bandyopadhyay, Jayasimha Atulasimha

Graduate Research Posters

We are experimenting on designing a voltage-controlled ultra-low-energy Magnetic Tunneling Junction (MTJ) device using a soft single domain magnetostrictive layer (i.e. Galfenol: Fe_1-xGa_x , x = 20 At%) coupled to a piezoelectric layer (i.e. PMN-PT). Special metal pads have been designed using photolithography to generate stress in the PMN-PT layer by applying electric field. The patterns of different shape anisotropic nano-magnets are designed using e-beam lithography and we have successfully fabricate FeGa nanomagnets with only 12 to 13 nanometer thickness by sputter deposition. These nanomagnets have been characterized by magnetic force microscopy for observing their switching capabilities. …

Hybrid Silicon Mode-Locked Laser With Improved Rf Power By Impedance Matching, Bassem M. Tossoun

Master's Theses

The mode-locked laser diode (MLLD) finds a lot of use in applications such as ultra high-speed data processing and sampling, large-capacity optical fiber communications based on optical time-division multiplexing (OTDM) systems. Integrating mode-locked lasers on silicon makes way for highly integrated silicon based photonic communication devices. The mode-locked laser being used in this thesis was built with Hybrid Silicon technology. This technology, developed by UC Santa Barbara in 2006, introduced the idea of wafer bonding a crystalline III- V layer to a Silicon-on-insulator (SOI) substrate, making integrated lasers in silicon chips possible.

Furthermore, all mode-locked lasers produce phase noise, which …

Mos Current Mode Logic (Mcml) Analysis For Quiet Digital Circuitry And Creation Of A Standard Cell Library For Reducing The Development Time Of Mixed Signal Chips, David Marusiak

Master's Theses

Many modern digital systems use forms of CMOS logical implementation due to the straight forward design nature of CMOS logic and minimal device area since CMOS uses fewer transistors than other logic families. To achieve high-performance requirements in mixed-signal chip development and quiet, noiseless circuitry, this thesis provides an alternative toCMOSin the form of MOS Current Mode Logic (MCML). MCML dissipates constant current and does not produce noise during value changing in a circuit CMOS circuits do. CMOS logical networks switch during clock ticks and with every device switching, noise is created on the supply and ground to deal with …

Nano-Ionic Radiation Sensor: Materials Engineering, Device Design, And Testing, Mahesh Satyanarayana Ailavajhala

Boise State University Theses and Dissertations

For decades, various radiation-detecting materials have been extensively researched, to find a better material or mechanism. Recently, there has been a growing need for smaller, and more effective materials or devices that are Integrated Circuits (IC) compatible, and can perform similar functions as bulkier Geiger counters, and other measurement options, which fail the requirement for easy, cheap, and accurate radiation dose measurements. Here arises the use of thin films of chalcogenide glasses, which have unique properties of high thermal stability along with high sensitivity towards short wavelength radiation.

In this work, the effect of γ-rays, generated from a ⁶⁰Co …

Electron – Phonon Interaction In Multiple Channel Gan Based Hfets: Heat Management Optimization, Romualdo A. Ferreyra

Theses and Dissertations

New power applications for managing increasingly higher power levels require that more heat be removed from the power transistor channel. Conventional treatments for heat dissipation do not take into account the conversion of excess electron energy into longitudinal optical (LO) phonons, whose associated heat is stored in the channel unless such LO phonons decay into longitudinal acoustic (LA) phonons via a Ridley path. A two dimensional electron gas (2DEG) density of ~5×10¹²cm^-2 in the channel results in a strong plasmon–LO phonon coupling (resonance) and a minimum LO phonon lifetime is experimentally observed, implying fast heat removal from …

A Multi-Physics Computational Approach To Simulating Thz Photoconductive Antennas With Comparison To Measured Data And Fabrication Of Samples, Darren Ray Boyd

Theses and Dissertations--Electrical and Computer Engineering

The frequency demands of radiating systems are moving into the terahertz band with potential applications that include sensing, imaging, and extremely broadband communication. One commonly used method for generating and detecting terahertz waves is to excite a voltage-biased photoconductive antenna with an extremely short laser pulse. The pulsed laser generates charge carriers in a photoconductive substrate which are swept onto the metallic antenna traces to produce an electric current that radiates or detects a terahertz band signal. Therefore, analysis of a photoconductive antenna requires simultaneous solutions of both semiconductor physics equations (including drift-diffusion and continuity relations) and Maxwell’s equations. A …

Investigation Of The Effects Of Rapid Thermal Annealing On Mbe Grown Gaasbi/Gaas Heterostructures For Optoelectronic Devices, Perry C. Grant

Graduate Theses and Dissertations

High efficiency optoelectronic devices rely on high quality materials making up the device structure. The scope of this thesis investigates the effectiveness of rapid thermal annealing (RTA) at improving the material quality of GaAsBi/GaAs heterostructures. During the fabrication of a device, the contacts of the device had the rapid thermal annealing process accomplished to produce ohmic contacts and this research explored if this annealing treatment degraded the quantum wells that made up the active region of a device. To investigate these effects, a system to measure the photoluminescence of the material system was constructed utilizing Fourier Transform Infrared Spectroscopy. The …

Mems Lab Simulation Tool, Oluwatosin D. Adeosun, Sambit Palit, Ankit Jain, Muhammad A. Alam

The Summer Undergraduate Research Fellowship (SURF) Symposium

MEMS actuators have multiple design applications. Understanding their behavior as well as the ability to predict their actuation characteristics and voltage response is important when designing these actuators. In order to know these devices will behave, designers have to solve multiple analytical equations and experiments that can be very time consuming. Over the course of the summer a tool was created on nanoHUB that will allow users to enter information about a MEMS actuator and provide the voltage response of the actuator. To create the tool, scaling equations were first provided for various geometry configurations and the equations were next …