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Si Based Quantum Functional Tunneling Devices And Their Applications To Logic And Other Future Circuit Topologies
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Book Synopsis Si-based Quantum Functional Tunneling Devices and Their Applications to Logic and Other Future Circuit Topologies by : Niu Jin
Download or read book Si-based Quantum Functional Tunneling Devices and Their Applications to Logic and Other Future Circuit Topologies written by Niu Jin and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The aim of this Ph. D. project is to develop high performance Si-based tunneling structures for integrated circuitry applications. In this work, three kinds of Si-based tunneling structures, namely, Si-based resonant interband tunneling diodes (RITD) for mixed signal integrated circuit and low power digital applications, Si-based backward diode for millimeterwave detection applications, and fabrication of Ge quantum dots for single electron transistor (SET) and quantum-dot cellular automata (QCA) applications, were studied. Both the RITD structure and post-growth annealing process were optimized to raise the peak-to-valley current ratio. Studies were performed to both maximize and minimize the peak current density for two different types of circuit applications. A low power one-transistor tunnel diode SRAM was demonstrated using the low current density RITD developed. Vertically integrated RITDs showing two successive NDR regions under the forward biasing condition are presented. Subsequently, tri-state logic was demonstrated. A comprehensive model which combines both the small and large signal models of RITDs was developed. The microwave performance of RITDs is also discussed. Several simple RITD circuits are simulated using this model. Radiation experiment on the Si-based RITD provides experimental evidence for resonant tunneling as opposed to Esaki-like tunneling. RITDs were grown on SiGe substrate to engineer the band offsets by strain modification. Si-based backward diodes for zero-biased millimeter wave detection are studied. The high sensitivity and SiGe HBT compatibility of the Si-based backward diodes make them very attractive for zero-bias millimeter-wave detector applications. Fabrication of Ge quantum dot by oxidizing Si and SiGe nano-pillars for QCA applications was presented. Overall, the work presented here was to extend Si technology, as articulated on the International Technology Roadmap for semiconductors, and can serve as a guide for the future exploitation of Si-based RITDs.
Book Synopsis Tunneling Based Quantum Functional Devices and Circuits for Low Power VLSI Design by : Anisha Ramesh
Download or read book Tunneling Based Quantum Functional Devices and Circuits for Low Power VLSI Design written by Anisha Ramesh and published by . This book was released on 2012 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Handheld devices, such as cellphones, dominate consumer electronics market today and are foreseen to grow further in future years. One of the primary challenges with these devices is reducing the power consumption while keeping the operating frequencies high. Scaling of transistor dimensions has contributed to both increasing chip operating frequencies and greater functionality per unit area. However, as dimensions enter a few 10's of nanometer, leakage currents have also increased, escalating the overall power consumption. Scaling of supply voltage is a key to keep both dynamic and static power consumption low. Tunneling-based devices are investigated to address this challenge. Tunnel diodes in conjunction with conventional transistors can be used in novel circuit topologies to develop high speed circuits operating below 0.5V. However, large scale manufacture requires a Si-based device structure that can be fabricated with tools compatible with standard CMOS processing. In this dissertation, Si-based resonant interband tunnel diodes (RITD) are fabricated using chemical vapor deposition (CVD). High peak to valley current ratio's (PVCR) of 5.2 are obtained through optimization of the boron [delta]-doping with peak current densities of 20 A/cm2. This is the largest PVCR for silicon based tunnel diodes fabricated using CVD. Further, integration into a standard electronic design automation (EDA) tools is essential to enable development of very large scale integrated (VLSI) circuits. Tunnel diodes have been integrated into the Cadence EDA tool and a 32 x 32 bit tunneling SRAM (TSRAM) memory array has been designed with a standard 90 nm product development kit (PDK) obtained from MOSIS, for use as embedded memory. This provides a platform to compare TSRAM performance with the currently dominant SRAM and embedded DRAM technologies. Its performance and robustness to process variation is evaluated for a supply voltage of 0.5V. Read access times of 1 ns and write access times of 0.5 ns are obtained with a standby power dissipation of 6e-5 mW/cell and dynamic power dissipation of 1.8e-7 mW/MHz per cell. These are comparable to the 90 nm SRAM specifications obtained from the international technology roadmap for semiconductors (ITRS). Tunnel FETs are a promising alternate to MOSFETs for low power design due to the ability to scale threshold voltage and hence supply voltage, without increase in OFF currents. However, they suffer from low ON currents. Prior experience with tunnel diode optimization is used to investigate new TFET structures to improve tunneling ON currents. A 300 nm channel Si vertical p-TFET with an n [delta]-doping has an ON current of 0.05 uA/um at a VDS of 2.5V with an ION-IOFF ratio of 104. Addition of Ge in the channel, to form a for a 30 nm Si0.9Ge0.1 channel, enhances the ON current to 4.8 uA/um at a VDS of 2V.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 780 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantum Functional Devices with Extended CMOS Technologies and Various Applications Including Millimeter-wave Detectors by : Si Young Park
Download or read book Quantum Functional Devices with Extended CMOS Technologies and Various Applications Including Millimeter-wave Detectors written by Si Young Park and published by . This book was released on 2009 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The International Technology Roadmap for Semiconductors (ITRS) forecasts that current semiconductor technology based on the mainstream silicon CMOS platform is approaching its scaling limit. One emerging technology which may augment CMOS and extend its operational lifetime is tunneling devices together with transistors. Tunnel diode based circuits have superior performance regarding high speed operation concurrently with low power consumption. Si-based resonant interband tunnel diodes (RITD) developed by this research group that are grown epitaxially using atmospheric pressure/reduced pressure chemical vapor deposition (AP/RP-CVD) and low temperature molecular beam epitaxy (LT-MBE), now enable monolithic integration with Si CMOS and SiGe technology. This thesis focuses on the study of improvement of the performance of RITD samples grown by CVD and LT-MBE epitaxy technology including silicon-based backward diodes for direct detection of millimeter radiation, SiGe nanopillars to form Ge quantum dots for quantum-dot cellular automata (QCA), and the plasma damage from inductively-coupled plasma reactive ion etching (ICP-RIE) processes. Based on the research studies, the SiGe RITDs shows tremendous potential for future device market opportunities with numerous applications.
Book Synopsis Quantum Devices Using Si-Based Superlattices and Structures by : Kang L. Wang
Download or read book Quantum Devices Using Si-Based Superlattices and Structures written by Kang L. Wang and published by . This book was released on 1993 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of the research was to perform scientific study and experimentation on potential new Si-based devices for future optical and electronic applications. The research areas included novel detectors, sources, new properties, and other quantum devices using Si molecular beam epitaxy (Si-MBE) based superlattices and superstructures. With the current ARO support, we have made significant advances in the understanding of optical properties of intersubband transition of SiGe/Si multiple quantum wells, and the fabrication of multiple quantum well infrared detectors operating in the mid infrared range. Large many-body effects have been observed in heavily doped Si and SiGe/Si quantum well structures. Normal incidence intersubband transitions have been demonstrated for both n and p type SiGe/Si quantum well structures. For potential realization of Si-based light sources we have studied the luminescence from monolayer superlattices and strained alloy layers. In the area of quantum transport, a resonant tunneling transistor has been demonstrated ... Intersubband, Quantum Transport, Many-body Effects, Superlattices, Infrared Detectors.
Book Synopsis Technology of Quantum Devices by : Manijeh Razeghi
Download or read book Technology of Quantum Devices written by Manijeh Razeghi and published by Springer Science & Business Media. This book was released on 2009-12-11 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technology of Quantum Devices offers a multi-disciplinary overview of solid state physics, photonics and semiconductor growth and fabrication. Readers will find up-to-date coverage of compound semiconductors, crystal growth techniques, silicon and compound semiconductor device technology, in addition to intersubband and semiconductor lasers. Recent findings in quantum tunneling transport, quantum well intersubband photodetectors (QWIP) and quantum dot photodetectors (QWDIP) are described, along with a thorough set of sample problems.
Book Synopsis High Speed Quantum Device and Circuits: Modeling and Design. Phase 1 by :
Download or read book High Speed Quantum Device and Circuits: Modeling and Design. Phase 1 written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document summarizes work carried out under a U.S. Navy SBIR study, Topic N99-02. The goal of the study was to develop a robust, portable, user-friendly, validated quantum device algorithm for designing tunneling devices, in particular resonant tunneling devices, for realistic present, near future and future applications. Successful algorithm development based on the space and time dependent Wigner equation was undertaken with the result that SRA has, in place, a transient algorithm for calculating the switching properties of resonant tunneling devices under a variety of conditions. The algorithm includes design information with respect to contacts, dissipation and the external circuit. The effects of noise were briefly studied, and recommendations were made for further work to permit the implementation of the algorithm for the design of a 100+GHz clock.
Book Synopsis Progress Towards Two-qubit Devices in Si/sige Heterostructures by : Ryan Howard Foote
Download or read book Progress Towards Two-qubit Devices in Si/sige Heterostructures written by Ryan Howard Foote and published by . This book was released on 2018 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since being proposed almost 40 years ago, scientists across many disciplines have made great progress in the fields of quantum computation and quantum information. Instead of a classical bit (0 or 1), a quantum computer uses a two-level quantum system as a quantum bit or qubit. By controllably manipulating the quantum-mechanical properties of these qubits, a quantum computer could, for example, be used to simulate other, less well understood quantum systems, or to run certain classes of quantum algorithms that cannot be run on classical hardware. In order to build a quantum computer, certain basic requirements must be met. As with a classical computer, logic gates are necessary to controllably manipulate qubits to perform calculations. One such requirement for a universal quantum computer is a two-qubit logic gate. This is an inherently quantum mechanical gate, which has no classical analog. For example, the controlled-not two-qubit gate will perform a not operation on the target qubit if and only if the control qubit is in the one state, else it does nothing to the target qubit. In either case, the control qubit is left unchanged and unmeasured. Being able to perform this gate with high fidelity is critical to creating a quantum computer. In this dissertation, I present progress towards fabricating, characterizing, and manipulating two-qubit devices in Si/SiGe heterostructures. First, I motivate the use of quantum dot qubits hosted in Si/SiGe as a suitable platform for quantum computing. Then, I present characterization of Si/SiGe substrates and discuss fabrication of a quantum dot device. Next, I outline the electronics set up for measuring a quantum dot device in a dilution refrigerator. I then present results of two, published experiments which explore multi-qubit systems: one which demonstrates controllable tunnel coupling between a quantum dot an a nearby localized impurity, and the other which demonstrates state-conditional Landau-Zener-Stückelberg oscillations between capacitively coupled double quantum dots in a quadruple quantum dot device. Next I discuss fabrication and characterization of micromagnets for spin qubit applications. I finally conclude by discussing future research avenues towards realizing a robust, multi-qubit device in silicon.
Book Synopsis Electrical & Electronics Abstracts by :
Download or read book Electrical & Electronics Abstracts written by and published by . This book was released on 1997 with total page 2092 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Study on the Tunnel Barrier in a Top-gated Si/SiGe Quantum Device by :
Download or read book A Study on the Tunnel Barrier in a Top-gated Si/SiGe Quantum Device written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tunneling of an electron is one of the well-studied phenomena. It also found many commercial applications including tunnel diodes. In top-gated semiconductor quantum dot spin qubits, the voltage controlled tunnel barriers formed by top gates are the fundamental building block to build qubit. Moreover, energy dependence of the tunnel rate in such barriers is well utilized in many qubit measurements including single shot read out of a spin. There have been only a few studies in energy dependent tunneling in top-gated quantum dot devices. Also there has not been much study on the tunnel barrier itself. The barrier information such as height, length, and shape of the barrier is important to understand the dot system and to understand the energy dependent tunneling, which is critical in qubit operation. In this thesis research, we studied the tunnel barrier in a top gated Si/SiGe quantum device. We measured temperature dependence of the tunneling conductance, where we determined the height of the barrier by activation energy. Using the experimentally determined height of the barrier, we developed simple, empirical two-dimensional (2D) barrier models based on molecular coherent tunneling theory. The calculated tunneling conductance well fit to the experimental conductance. Using the developed models, we determined energy dependent tunneling coefficients, which agree well with experimental values that determined from pulsed gate tunnel rate measurements, performed in a dot using similar Si/SiGe heterostructure. The results suggest that the shape of the barrier is parabolic as we expected. Finally, we compared the barrier shape with conventional 1D models to check the impact of the dimensionality.
Book Synopsis InGaAs/GaAsSb Quantum-well Tunnel-FETs for Ultra-low Power Applications by : Tao Yu (Ph. D.)
Download or read book InGaAs/GaAsSb Quantum-well Tunnel-FETs for Ultra-low Power Applications written by Tao Yu (Ph. D.) and published by . This book was released on 2016 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Tunnel-FET (TFET), where carrier injection is determined by gate-controlled tunneling from the source to the channel, has been attractive as one of the promising candidates for future ultra-low power applications. In this thesis, inline-TFETs with tunneling direction aligned to the gate electric field are designed, fabricated and analyzed based on InGaAs/GaAsSb material. Using ultrathin InGaAs/GaAsSb quantum-well (QW), the device fabrication technology was developed and the tunneling properties of two successive generations of QWTFETs were investigated. In the first generation QWTFETs, the limitation of gate oxide quality on InGaAs and parasitic thermal currents manifests itself in degraded subthreshold swing (SS) of 140 mV/dec, as well as strongly temperature dependent SS from 300 K to 77 K. The second generation QWTFETs with sub-nm InP cap between gate oxide and InGaAs channel and revised structure design has demonstrated improved SS of 87 mV/dec at 300 K and temperature independent SS below 140 K, indicating the achievable tunneling current steepness with the current device design. Physical modeling and quantum simulations based on the low temperature I-V characteristics were used to analyze the fundamental gate efficiency of the experimental QWTFETs in order to reveal the ultimate intrinsic tunneling steepness of the InGaAs/GaAsSb tunneling junction. The extracted gate efficiency around 55-64% is due to the coupling of the gate capacitance and tunneling junction capacitance and degrades dramatically the attainable SS in the QWTFET. On the other hand, the implied intrinsic tunneling steepness of the InGaA/GaAsSb is around 30 mV/dec, almost identical to previously reported non-abruptness of the conduction/valence band-edge into the bandgap. The result indicates the possibility of achieving SS as low as 38 mV/dec in QWTFETs by improving gate efficiency by up to 78% with proposed optimized parameters based on simulation results. Non-logic TFET-specific circuits are also explored to understand the advantage of TFETs in real-world applications. Due to the superior nonlinearity in the device I-V characteristics and gate-dependent negative-differential-resistance (NDR) under forward bias condition (VDS
Book Synopsis Interband Quantum Tunneling at the Band-edges in III-V Semiconductor Heterojunctions for Low-power Logic and Detectors by : Ryan Michael Iutzi
Download or read book Interband Quantum Tunneling at the Band-edges in III-V Semiconductor Heterojunctions for Low-power Logic and Detectors written by Ryan Michael Iutzi and published by . This book was released on 2015 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explores interband tunneling in semiconductor heterojunctions where a density-of-states switching mechanism can be used to sharply modulate the junction conductance using small applied voltages via alignment and misalignment of the band-edges. Such a mechanism is useful for the pursuit of low-power logic devices as well as nonlinear analog components such as square-law detectors. In the former application, density-of-states switching can potentially allow for transistor subthreshold slopes steeper than the room-temperature thermal limit of 60 mV/decade in a device known as a tunnel field effect transistor (TFET), and in the latter application, it can allow for curvature coefficients greater than the thermal limit of 38.7 V-1. However, predictions of stellar performance from simulation studies have not yet been matched experimentally, particularly in the area of TFETs, which have not produced a density-of-states switching device steeper than the thermal limit. To date however, the true steepness obtainable from density-of-states switching (band-edge steepness), and what affects it, remains unknown. This thesis fundamentally studies the band-edge steepness and how it depends on various factors including interfacial crystal defects, inhomogeneity, temperature, and band alignment. Using type-III band alignment epitaxially grown InAs/GaSb heterojunctions, as well as both type-II and type-III band alignment InGaAs/GaAsSb heterojunctions, it is identified that point defects gettered by dislocations at the interface as well as uneven distributions of point defects and composition can lead to both interfacial energy states and nonuiform band-alignment across the tunnel junction that result in poorer band-edge steepness. We identify a variety of techniques to improve the junction interface quality and demonstrate a corresponding improvement in band-edge steepness. We also determine that in our two-terminal devices designed to deconvolute TFET parasitics, the band-edge steepness does not depend on temperature, contrasting strongly with published TFET results and indicating that TFETs designed to utilize density-of-states switching are likely not actually harvesting interband tunneling and are instead dominated by thermally-activated parasitics. Using the various conclusions of our fundamental work as design guidelines, we develop and demonstrate an InGaAs/GaAsSb materials system integrated on an InP platform with a record 76 mV/decade band-edge steepness and 43 V-1 curvature coefficient near zero-bias.
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Single-Electron Tunneling and Mesoscopic Devices by : K.v. Klitzing
Download or read book Single-Electron Tunneling and Mesoscopic Devices written by K.v. Klitzing and published by Springer. This book was released on 2011-11-22 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-electron tunneling (SET) and related phenomena have recently come to be considered as "hot topics". This also became apparent when we organized the 4th International Conference on Superconducting and Quantum Effect Devices and Their Applications, SQUID'91, which was held June 18-21, 1991, in Berlin, Germany. Impressed by the number of contributions dedicated to the new physics of ultrasmall devices, we deemed it appropriate to devote this volume of the Springer Series in Electronics and Photonics to these specialized proceedings. The other contributions presented at SQUID'91, which are more conventional in character but nevertheless contain excitingly innovative results, are published separately as Volume 64 of the series Springer Proceedings in Physics. At first glance it seems strange that a conference abbreviated SQUID'91 should attract so many papers on non-superconducting devices, and in fact the first SQUID'XX conferences dealt exclusively with the physics and technology of Josephson junctions, SQUIDs and other superconducting devices and their ap plications. However, many concepts developed for superconducting devices, like tunneling, flux quantization, and flux-charge conjugation, appeared to be suitable for ultrasmall non-superconducting structures as well, and many researchers in the field of superconducting devices extended their activities accordingly. Thus the extension of the conference programme evolved quite informally. Meanwhile, the meetings established themselves as well-known conference series tradition ally appreciated by the SQUID community for its balanced mixture of physics and technology, review and preview. SQUID'XX became a kind of a trademark.
Book Synopsis Quantum Dot Devices by : Zhiming M. Wang
Download or read book Quantum Dot Devices written by Zhiming M. Wang and published by Springer Science & Business Media. This book was released on 2012-05-24 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum dots as nanomaterials have been extensively investigated in the past several decades from growth to characterization to applications. As the basis of future developments in the field, this book collects a series of state-of-the-art chapters on the current status of quantum dot devices and how these devices take advantage of quantum features. Written by 56 leading experts from 14 countries, the chapters cover numerous quantum dot applications, including lasers, LEDs, detectors, amplifiers, switches, transistors, and solar cells. Quantum Dot Devices is appropriate for researchers of all levels of experience with an interest in epitaxial and/or colloidal quantum dots. It provides the beginner with the necessary overview of this exciting field and those more experienced with a comprehensive reference source.
Book Synopsis Magnetic Multilayers by : Lawrence H Bennett
Download or read book Magnetic Multilayers written by Lawrence H Bennett and published by World Scientific. This book was released on 1994-12-16 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on an increasingly important area of materials science and technology, namely, the fabrication and properties of artificial materials where slabs of magnetized materials are sandwiched between slabs of nonmagnetized materials. It includes reviews by experts on the theory and descriptions of the various experimental techniques such as those using nuclear or electron spin probes, as well as optical, X-ray or neutron probes. It also reviews potential applications such as the giant magnetoresistance, and one specialized preparation technique, the electrodeposition. The various chapters are tutorial in nature, making the subject accessible to nonspecialists, as well as useful to researchers in the field.
Book Synopsis Computational Complexity by : Oded Goldreich
Download or read book Computational Complexity written by Oded Goldreich and published by Cambridge University Press. This book was released on 2008-04-28 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a comprehensive perspective to modern topics in complexity theory, which is a central field of the theoretical foundations of computer science. It addresses the looming question of what can be achieved within a limited amount of time with or without other limited natural computational resources. Can be used as an introduction for advanced undergraduate and graduate students as either a textbook or for self-study, or to experts, since it provides expositions of the various sub-areas of complexity theory such as hardness amplification, pseudorandomness and probabilistic proof systems.
