Nanotechnology Fabrication Commons^™

Design And Fabrication Of A Trapped Ion Quantum Computing Testbed, Christopher A. Caron

Masters Theses

Here we present the design, assembly and successful ion trapping of a room-temperature ion trap system with a custom designed and fabricated surface electrode ion trap, which allows for rapid prototyping of novel trap designs such that new chips can be installed and reach UHV in under 2 days. The system has demonstrated success at trapping and maintaining both single ions and cold crystals of ions. We achieve this by fabricating our own custom surface Paul traps in the UMass Amherst cleanroom facilities, which are then argon ion milled, diced, mounted and wire bonded to an interposer which is placed …

Thermal Transport Across 2d/3d Van Der Waals Interfaces, Cameron Foss

Doctoral Dissertations

Designing improved field-effect-transistors (FETs) that are mass-producible and meet the fabrication standards set by legacy silicon CMOS manufacturing is required for pushing the microelectronics industry into further enhanced technological generations. Historically, the downscaling of feature sizes in FETs has enabled improved performance, reduced power consumption, and increased packing density in microelectronics for several decades. However, many are claiming Moore's law no longer applies as the era of silicon CMOS scaling potentially nears its end with designs approaching fundamental atomic-scale limits -- that is, the few- to sub-nanometer range. Ultrathin two-dimensional (2D) materials present a new paradigm of materials science and …

Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian

Doctoral Dissertations

The self-assembly of charged macromolecules forms the basis of all life on earth. From the synthesis and replication of nucleic acids, to the association of DNA to chromatin, to the targeting of RNA to various cellular compartments, to the astonishingly consistent folding of proteins, all life depends on the physics of the organization and dynamics of charged polymers. In this dissertation, I address several of the newest challenges in the assembly of these types of materials. First, I describe the exciting new physics of the complexation between polyzwitterions and polyelectrolytes. These materials open new questions and possibilities within the context …

Modeling And Characterization Of Optical Metasurfaces, Mahsa Torfeh

Masters Theses

Metasurfaces are arrays of subwavelength meta-atoms that shape waves in a compact and planar form factor. During recent years, metasurfaces have gained a lot of attention due to their compact form factor, easy integration with other devices, multi functionality and straightforward fabrication using conventional CMOS techniques. To provide and evaluate an efficient metasurface, an optimized design, high resolution fabrication and accurate measurement is required. Analysis and design of metasurfaces require accurate methods for modeling their interactions with waves. Conventional modeling techniques assume that metasurfaces are locally periodic structures excited by plane waves, restricting their applicability to gradually varying metasurfaces that …

Towards Higher Power Factor In Semiconductor Thermoelectrics: Bandstructure Engineering And Potential Barriers, Adithya Kommini

Doctoral Dissertations

To keep up with the current energy demand and to sustain the growth requires efficient use of existing resources. One of the ways to improve efficiency is by converting waste heat to electricity using thermoelectrics. Thermoelectric devices work on the principle of Seebeck effect, where an applied temperature difference across the material results in a potential difference in the material. The possibility of drastic improvements in the efficiency of thermoelectric (TE) devices using semiconductor nanostructured materials renewed interest in thermoelectrics over the last three decades. Introducing confinement, interfaces, and quantum effects using nanostructures for additional control of charge and phonon …

Metasurface Design And Optimization With Adjoint Method, Mahdad Mansouree

Doctoral Dissertations

The invention and advancement of optical devices have tremendously changed our life. Devices such as cameras, displays and optical sensors are now an integral part of our lives. Moreover, with the rapid growth in new markets such as virtual reality (VR), augmented reality (AR), autonomous vehicles and internet of things (IoT) the need for optical devices is expected to grow considerably. Recent advances in nano-fabrication techniques have spurred a new wave of interest in optical metasurfaces. Metasurfaces are arrays of wisely selected nano-scattereres that generate desired transformation on the incident light. Metasurfaces provide a new platform for the development of …

Low-Energy Memristors & High-Nonlinearity Selector For Dense Passive Cross-Bar Arrays, Navnidhi K. Upadhyay

Doctoral Dissertations

Memristor or RRAM (Resistive Random Access Memory) based crossbar array architecture (CBA) is considered a leading contender for the next-generation non-volatile memory (NVM) as well as for future computing paradigms, such as in-memory computing, neuromorphic computing, neural networks, analog computing, reconfigurable computing, etc. Among many other attractive properties, memristors’ simple and dense 3D stackable structure is an essential enabler of these promising applications. However, the simplicity and high density of CBA comes at a price. CBA suffers from the so-called sneak path currents flowing through the unselected cells, which severely affects the read margin, makes CBA more power-hungry, increases the …

Thermal Transport Modeling Of Semiconductor Materials From First Principles, Aliya Qureshi

Masters Theses

Over the past few years, the size of semiconductor devices has been shrinking whereas the density of transistors has exponentially increased. Thus, thermal management has become a serious concern as device performance and reliability is greatly affected by heat. An understanding of thermal transport properties at device level along with predictive modelling can lead us to design of new systems and materials tailored according to the thermal conductivity. In our work we first review different models used to calculate thermal conductivity and examine their accuracy using the experimentally measured thermal conductivity for Si. Our results suggest that empirically calculated rates …

Direct Printing Of Conductive Inks For Organic Electronics And Wearable Microfluidics, Aditi Naik

Doctoral Dissertations

This dissertation examines the direct printing of conductive inks on polymeric substrates for applications in organic electronics, microfluidic valving systems, and wearable sweat sensors. The inexpensive production of solution-based electrodes with high electrical conductivity is necessary to enable the next-generation of printed, flexible, and organic electronics. Specifically, the optimization and printing of liquid-phase graphene ink and nanoparticle-based silver ink by soft nanoimprint lithography and inkjet-printing is discussed to achieve printed functional devices. Using scalable low-cost patterning systems, these flexible applications are compatible with roll-to-roll processing, enabling large-scale manufacturing. This research expands the knowledge of high-resolution printing optimization for the direct …

Parallel Algorithms For Time Dependent Density Functional Theory In Real-Space And Real-Time, James Kestyn

Doctoral Dissertations

Density functional theory (DFT) and time dependent density functional theory (TDDFT) have had great success solving for ground state and excited states properties of molecules, solids and nanostructures. However, these problems are particularly hard to scale. Both the size of the discrete system and the number of needed eigenstates increase with the number of electrons. A complete parallel framework for DFT and TDDFT calculations applied to molecules and nanostructures is presented in this dissertation. This includes the development of custom numerical algorithms for eigenvalue problems and linear systems. New functionality in the FEAST eigenvalue solver presents an additional level of …

Skybridge-3d-Cmos: A Fine-Grained Vertical 3d-Cmos Technology Paving New Direction For 3d Ic, Jiajun Shi

Doctoral Dissertations

2D CMOS integrated circuit (IC) technology scaling faces severe challenges that result from device scaling limitations, interconnect bottleneck that dominates power and performance, etc. 3D ICs with die-die and layer-layer stacking using Through Silicon Vias (TSVs) and Monolithic Inter-layer Vias (MIVs) have been explored in recent years to generate circuits with considerable interconnect saving for continuing technology scaling. However, these 3D IC technologies still rely on conventional 2D CMOS’s device, circuit and interconnect mindset showing only incremental benefits while adding new challenges reliability issues, robustness of power delivery network design and short-channel effects as technology node scaling. Skybridge-3D-CMOS (S3DC) is …

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 …

Materials Engineering, Switching Mechanism And Novel Applications Of Memristive Devices, Hao Jiang

Doctoral Dissertations

Memristive devices have attracted tremendous interests because of their highly desirable properties such as a simple structure, low switching voltage, fast switching speed, excellent scalability, multiple conductance states and great compatibility with the Complementary Metal–Oxide–Semiconductor technology. Hence, they stand out as promising candidates for next-generation non-volatile memory and electronic synapses in artificial neural network. This thesis reports systematic studies of the memristive switching phenomena in oxide based material systems, in aspects of materials engineering, switching mechanism and novel applications. We demonstrated efficient ways of engineering device performances such as metal doping and further presented a highly reliable hafnium oxide based …

Analog Computing Using 1t1r Crossbar Arrays, Yunning Li

Masters Theses

Memristor is a novel passive electronic device and a promising candidate for new generation non-volatile memory and analog computing. Analog computing based on memristors has been explored in this study. Due to the lack of commercial electrical testing instruments for those emerging devices and crossbar arrays, we have designed and built testing circuits to implement analog and parallel computing operations. With the setup developed in this study, we have successfully demonstrated image processing functions utilizing large memristor crossbar arrays. We further designed and experimentally demonstrated the first memristor based field programmable analog array (FPAA), which was successfully configured for audio …

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 …

Skynet: Memristor-Based 3d Ic For Artificial Neural Networks, Sachin Bhat

Masters Theses

Hardware implementations of artificial neural networks (ANNs) have become feasible due to the advent of persistent 2-terminal devices such as memristor, phase change memory, MTJs, etc. Hybrid memristor crossbar/CMOS systems have been studied extensively and demonstrated experimentally. In these circuits, memristors located at each cross point in a crossbar are, however, stacked on top of CMOS circuits using back end of line processing (BOEL), limiting scaling. Each neuron’s functionality is spread across layers of CMOS and memristor crossbar and thus cannot support the required connectivity to implement large-scale multi-layered ANNs.

This work proposes a new fine-grained 3D integrated circuit technology …

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 …

Skybridge: A New Nanoscale 3-D Computing Framework For Future Integrated Circuits, Mostafizur Rahman

Doctoral Dissertations

Continuous scaling of CMOS has been the major catalyst in miniaturization of integrated circuits (ICs) and crucial for global socio-economic progress. However, continuing the traditional way of scaling to sub-20nm technologies is proving to be very difficult as MOSFETs are reaching their fundamental performance limits [1] and interconnection bottleneck is dominating IC operational power and performance [2]. Migrating to 3-D, as a way to advance scaling, has been elusive due to inherent customization and manufacturing requirements in CMOS architecture that are incompatible with 3-D organization. Partial attempts with die-die [3] and layer-layer [4] stacking have their own limitations [5]. We …

Architecting Np-Dynamic Skybridge, Jiajun Shi

Masters Theses

With the scaling of technology nodes, modern CMOS integrated circuits face severe fundamental challenges that stem from device scaling limitations, interconnection bottlenecks and increasing manufacturing complexities. These challenges drive researchers to look for revolutionary technologies beyond the end of CMOS roadmap. Towards this end, a new nanoscale 3-D computing fabric for future integrated circuits, Skybridge, has been proposed [1]. In this new fabric, core aspects from device to circuit style, connectivity, thermal management and manufacturing pathway are co-architected in a 3-D fabric-centric manner.

However, the Skybridge fabric uses only n-type transistors in a dynamic circuit style for logic and memory …

Development Of Infrared And Terahertz Bolometers Based On Palladium And Carbon Nanotubes Using Roll To Roll Process, Amulya Gullapalli

Masters Theses

Terahertz region in the electromagnetic spectrum is the region between Infrared and Microwave. As the Terahertz region has both wave and particle nature, it is difficult to make a room temperature, fast, and sensitive detector in this region. In this work, we fabricated a Palladium based IR detector and a CNT based THz bolometer.

In Chapter 1, I give a brief introduction of the Terahertz region, the detectors already available in the market and different techniques I can use to test my detector. In Chapter 2, I explain about the Palladium IR bolometer, the fabrication technique I have used, and …

Millimeter Wave Indium Phosphide Heterojunction Bipolar Transistors: Noise Performance And Circuit Applications, Metin Ayata

Masters Theses

The performance of III-V heterojunction bipolar transistors (HBTs) has improved significantly over the past two decades. Today’s state of the art Indium Phosphide (InP) HBTs have a maximum frequency of oscillation greater than 800 GHz and have been used to realize an amplifier operating above 600 GHz . In comparison to silicon (Si) based devices, III-V HBTs have superior transport properties that enables a higher gain, higher speed, and noise performance, and much higher Johnson figure- of-merit . From this perspective, the InP HBT is one of the most promising candidates for high performance mixed signal electronic systems.

A Novel Reconfiguration Scheme In Quantum-Dot Cellular Automata For Energy Efficient Nanocomputing, Madhusudan Chilakam

Masters Theses 1911 - February 2014

Quantum-Dot Cellular Automata (QCA) is currently being investigated as an alternative to CMOS technology. There has been extensive study on a wide range of circuits from simple logical circuits such as adders to complex circuits such as 4-bit processors. At the same time, little if any work has been done in considering the possibility of reconfiguration to reduce power in QCA devices. This work presents one of the first such efforts when considering reconfigurable QCA architectures which are expected to be both robust and power efficient. We present a new reconfiguration scheme which is highly robust and is expected to …

Parameter Variation Sensing And Estimation In Nanoscale Fabrics, Jianfeng Zhang

Masters Theses 1911 - February 2014

Parameter variations introduced by manufacturing imprecision are becoming more influential on circuit performance. This is especially the case in emerging nanoscale fabrics due to unconventional manufacturing steps (e.g., nano-imprint) and aggressive scaling. These parameter variations can lead to performance deterioration and consequently yield loss.

Parameter variations are typically addressed pre-fabrication with circuit design targeting worst-case timing scenarios. However, this approach is pessimistic and much of performance benefits can be lost. By contrast, if parameter variations can be estimated post-manufacturing, adaptive techniques or reconfiguration could be used to provide more optimal level of tolerance. To estimate parameter variations during run-time, on-chip …

N3asics: Designing Nanofabrics With Fine-Grained Cmos Integration, Pavan Panchapakeshan

Masters Theses 1911 - February 2014

Nanoscale-computing fabrics based on novel materials such as semiconductor nanowires, carbon nanotubes, graphene, etc. have been proposed in recent years. These fabrics employ unconventional manufacturing techniques like Nano-imprint lithography or Super-lattice Nanowire Pattern Transfer to produce ultra-dense nano-structures. However, one key challenge that has received limited attention is the interfacing of unconventional/self-assembly based approaches with conventional CMOS manufacturing to build integrated systems.

We propose a novel nanofabric approach that mixes unconventional nanomanufacturing with CMOS manufacturing flow and design rules to build a reliable nanowire-CMOS 3-D integrated fabric called N³ASICs with no new manufacturing constraints. In N³ASICs …

Towards Logic Functions As The Device Using Spin Wave Functions Nanofabric, Prasad Shabadi

Masters Theses 1911 - February 2014

As CMOS technology scaling is fast approaching its fundamental limits, several new nano-electronic devices have been proposed as possible alternatives to MOSFETs. Research on emerging devices mainly focusses on improving the intrinsic characteristics of these single devices keeping the overall integration approach fairly conventional. However, due to high logic complexity and wiring requirements, the overall system-level power, performance and area do not scale proportional to that of individual devices.

Thereby, we propose a fundamental shift in mindset, to make the devices themselves more functional than simple switches. Our goal in this thesis is to develop a new nanoscale fabric paradigm …

Terahertz Radiation From Single Walled Carbon Nanotubes, Martin M. Muthee

Masters Theses 1911 - February 2014

The Terahertz region of the electromagnetic spectrum is the region between microwaves and infra-red, dubbed the terahertz 'gap' due to its relative underdevelopment in terms of technology. This region is marked by expensive and inconvenient sources that are bulky or that require cryogenic cooling for normal operation, therefore creating a need for cheap and easy to use terahertz sources.

Carbon nanotubes have received considerable attention since their discovery due to their unique physical and electronic properties. Many applications have been proposed using especially Single-Walled Carbon Nanotubes (SWCNTs), and a number of commercial technologies exist. In this work, we have proposed …

Terahertz And Microwave Detection Using Metallic Single Wall Carbon Nanotubes, Enrique A. Carrion

Masters Theses 1911 - February 2014

Carbon nanotubes (CNTs) are promising nanomaterials for high frequency applications due to their unique physical characteristics. CNTs have a low heat capacity, low intrinsic capacitance, and incredibly fast thermal time constants. They can also exhibit ballistic transport at low bias, for both phonons and electrons, as evident by their fairly long mean free paths. However, despite the great potential they present, the RF behavior of these nanostructures is not completely understood. In order to explore this high frequency regime we studied the microwave (MW) and terahertz (THz) response of individual and bundled single wall nanotube based devices. This thesis is …