This book has its genesis in the 11th International Conference on Nanotechnology, the IEEE Nanotechnology Council’s flagship conference, held in Portland, Oregon, 15–19 August 2011. This is first and foremost an engineering conference, with the research papers presented having more of an applied bias than is typical at most contemporary nanoscience and nanotechnology conferences which generally still focus on the science of this nascent field. The initial proposition was to bring the broadest possible range of this material to the attention of the wider nanotechnology community, but with nearly 400 presentations that was clearly impractical in one book. Nanomaterials was the largest single track, but an analysis and characterization of all the papers presented revealed two other threads running through most of them: either devices or applications or both. So the decision was made to limit the content to nanodevice applications, albeit liberally interpreted in some cases, eliminating all of the nanometrology, nanopackaging, nanophotonics, nanorobotics, quantum computing, nanotechnology education and commercialization, EHS issues, and most of the nanomaterials, nanotechnology in energy, and nano-biomedicine from consideration for inclusion, but providing a more coherent focus on the broad range of nanoelectronics. There is a wealth of information contained in these other areas, and interested readers are referred to the proceedings archive in IEEE Xplore at: http://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?reload=true&punumber=6125891.
The response to invitations to authors to contribute was overwhelming, and what was initially envisaged as a standard 20-chapter monograph rapidly escalated into the much more comprehensive 68-chapter work. The book has been divided into sections for ease of navigation, and the Contents reveals both the breadth of topic coverage of the broad nanoelectronics field and depth in the inclusion of a number of chapters in each section, which reveal the diversity of research in each topic area. It must be emphasized that, notwithstanding the history above, the chapters are NOT the conference papers. Most have been expanded by at least 50% by the addition of extra material, typically additional new data or expanded applications context, but some report totally new work in the same area. So if a chapter herein whets the reader’s appetite for more information, it would be worth checking out the conference paper in IEEE Xplore before looking further afield.
The first two sections are appropriately enough devoted to nanoscale advances in current MOSFET/CMOS (metal–oxide–semiconductor field-effect transistor/complementary metal–oxide–semiconductor) technology, the first focused on modeling and simulation. Chapter 1 (Rodriguez and Huq) describes an application of the online nanodevice simulation tool at nano-HUB.org, while Chapters 2 (Ashraf et al.) and 3 (Li) adopt Monte Carlo approaches to simulate the effects of channel interface defect trapping on MOSFET threshold voltages. In the second section, Chapters 4 (Khaderbad and Rao) and 5 (Srivastava and Malhotra) consider self-assembled monolayer techniques and the deposition of La2O3/HfO2 gates, respectively, for nano-MOSFET performance enhancements, and Chapter 6 (Beg et al.) shows (by simulation) how varying device sizes in full adders can improve reliability (as determined by the static noise margin).
The next section contains four chapters on nano capacitors for four different applications. Chapter 7 (Sharma et al.) compares three technologies for electronics packaging. Chapter 8 (Arepalli) examines the effects of radiation on CNT composites and graphene for supercapacitors and field emission displays. Chapter 9 (Sayyad et al.) examines nanoparticle dispersions of an organic semiconductor for capacitive-type humidity sensors, and Chapter 10 (Li et al.) compares charge accumulation in SiO2 and Si3N4/SiO2 dielectric stacks for the control of stiction in capacitive MEMS/NEMS membrane devices.
Chapters 11 and 12 describe the fabrication of THz-capable devices. The nano-antenna arrays and MOM diodes for energy conversion described in Chapter 11 (Bareiβ et al.) can be fabricated at the requisite nanometer scale by nano-imprinting, and an InGaAs/InAlAs heterostructure is used for the novel Ballistic Deflection Transistor logic gates described in Chapter 12 (Wolpert and Ampadu).
Quantum–mechanical electron tunneling is the quintessential nanoscale phenomenon and drives much of the nanoelectronics field, whether intended or unintended. The first two chapters here, Chapters 13 (Ito et al.) and 14 (Karre et al.), describe different approaches to controlling the tunneling gap in single-electron transistor (SET) fabrication. Chapter 15 (Beiu et al.) uses SETs in its analysis of low-power axon-like communication, and Chapter 16 (D’Aloia et al.) describes the development of a sensitive mechanical stress sensor based on internal tunneling within a graphite nano-platelet composite.
The quantum cellular automata (QCA) chapters are natural successors to the SET section since the device state is also set by nanodot charging. However, Chapter 17 (Ottavi et al.) leads off by describing a magnetic variant of the QCA concept and demonstrates an HDL model for it. Chapter 18 (Kim and Swartzlander) presents a restoring divider circuit using more conventional QCAs, and Chapter 19 (Hook and Lee) describes a lattice implementation of QCA circuits at the molecular level for reliable room temperature operation. Chapter 20 (Wang et al.) returns to the problem of automated QCA circuit synthesis and the minimization of 4-variable logic functions.
Memristors offer considerable potential as both resistive switches and memory elements, and the next section is focused on memristors but also includes other examples of both. Chapter 21 (Delgado) presents a generalized treatment of the dynamic behavior of nonlinear nanodevices, but focuses primarily on memristors. Chapters 22 (Chen) and 23 (Linn et al.) are both concerned with the operation of crossbar memories, with Chapter 22 focused on the use of nonlinear resistive switches for sneak path reduction and Chapter 23 proposing and modeling antiserially connected memristors for the same purpose. Chapter 24 (Junsangsri and Lombardi) proposes and analyzes a memristor-based memory cell with ambipolar transistor controls. Chapter 25 (Cantley et al.) uses a memristor as the synapse in a neural learning circuit with nano-crystalline and nanoparticle thin-film transistors (TFTs). Finally, Chapter 26 (Maghsoudi and Martin) introduces a new memory concept, based on thermally actuated buckling of a nanoscale beam.
Graphene is the “material of the moment,” with enormous potential for nanoelectronics applications, and not only for devices. Consequently, the next section contains chapters devoted to the fabrication and properties of graphene as necessary precursors to device development. A stress-free process for the transfer of graphene from its growth substrate to its intended application is reported in Chapter 27 (Chen et al.) along with sheet resistance control by plasma treatments. Chapter 28 (Li et al.) describes an alternative dielectrophoretic transfer technique for precise positioning on a substrate and a pH sensor application. Two more transfer techniques are described in Chapter 29 (Rahman and Norton).
Chapter 30 (Nayfeh et al.) reports on the fabrication and performance of a GHz RF graphene MOSFET, while Chapter 31 (Yu et al.) demonstrates that breakdown currents in such devices can be significantly increased by replacing the usual SiO2 substrate layer with a more thermally conductive synthetic diamond. For active nanoelectronic devices, graphene must be converted from a semimetal to a semiconductor, and Chapter 32 (Plachinda et al.) reports that band gaps of up to 0.81 eV are achievable with metal-bis-arene chemical treatments.
Carbon nanotubes (CNTs) are definitely moving beyond research into development. The first CNT section is devoted to general applications, before moving on to CNT transistors. There is a great deal of interest in vertical CNT device interconnect for 3D system integration and Chapter 33 (Vollebregt et al.) examines top-down and bottom-up CNT fabrication at relatively low temperatures. Next, Chapters 34 (Chen et al.) and 35 (Aria et al.) present an output interface design for CNT infrared sensors and the exploitation of the CNT surface-to-volume ratio in electrolytic capacitor electrodes. Finally, Chapter 36 (Abdellah et al.) describes a spray deposition technique for the fabrication of CNT gas (NH3) sensors, and Chapter 37 (Aasmundtveit et al.) describes control of the synthesis temperature by Joule heating and of the growth direction by electric fields for CMOS/MEMS applications.
There are three sections devoted to CNT transistors, with the first two covering modeling and fabrication, in that order. Chapter 38 (Torres and Huq) extends a theoretical treatment of the bandgap variation with CNT diameter and temperature to its effects on transistor characteristics, and Chapter 39 (Chen et al.) uses time-dependent quantum mechanics to analyze CNT response to THz signals. Chapters 40 (Kato et al.) and 41 (Numata et al.) both address CNT TFT fabrication issues, with Chapter 40 reporting the stabilization of n-type CNT TFTs by Cs plasma irradiation and encapsulation, and Chapter 41 demonstrating printed CNT TFTs on flexible substrates.
The next two sections deal with the problems presented by a high rate of defective devices, first in CNT transistor devices (e.g., due to the mix of metallic and semiconducting CNTs) and then generalized to device-independent architectures. Chapter 42 (Gong et al.) first presents the characteristics of a CNT network TFT, and then goes on to percolation modeling of random effects. Chapter 43 (Ashraf et al.) similarly considers the effects of CNT diameter and misalignment and unwanted metallic CNTs on device yield, and Chapter 44 (Zhang and Delgado-Frias) analyzes the performance of an 8-transistor CNT SRAM array with faulty cell tolerance, for example, also with metallic CNTs. Chapters 45 (Zawodniok and Kundaikar) and 46 (Aymerich et al.) describe, respectively, a novel built-in self-test for nanofabric architectures and an adaptive fault-tolerant redundant architecture to accommodate defective devices by weighted voting.
Nanowires are also covered in three sections: fabrication, applications, and transistors. Epitaxial GaAs nanowire growth on silicon substrates, as demonstrated in Chapter 47 (Kang et al.), permits the integration of III–V optoelectronics with Si-microelectronics. Fabrication of both p- and n-type single-crystal tin oxide nanowires is described in Chapter 48 (Tran and Rananavare) for a ppb chlorine sensor and other applications, and similarly Chapter 49 (Ng et al.) describes the fabrication of single-crystal copper silicide nanowires for Li-ion battery anode terminals. Finally, Graf et al. (Chapter 50) demonstrate the effects of pulsed electrodeposition on the fabrication of metallic nanowires for interconnect.
In the applications area, Chapter 51 (Gupta et al.) characterizes ZnO nanowires for biosensing, Park et al. (Chapter 52) have fabricated PN heterojunctions from both p- and n-type ZnO nanorods on porous silicon, and Dar et al. (Chapter 53) demonstrate the use of GaN nanowires coated with silver nanoparticles as surface enhancement Raman spectroscopy biosensors.
Next, Bayraktaroglu and Leedy (Chapter 54) examine the properties of transparent columnar ZnO TFTs, and Kyogoku et al. (Chapter 55) examine the effects of Si-nanowire shapes and roughness on the energy band gap, which will impact transistor applications. Chapters 56 (Hossain et al.) and 57 (Martinez et al.) continue with simulation studies of the impacts of a channel trap and a channel donor, respectively, on the ON currents in nanowire transistors, while Chapters 58 (Huang et al.) and 59 (Jeong et al.) both present the characteristics of “gate-all-around” devices, the former addressing minimization of performance variations and the latter, the extraction of parasitic parameters.
Nanomagnetic logic (NML) is receiving a great deal of attention for its potential in nonvolatile memories. Chapter 60 (Das et al.) proposes an integration of NML with magnetoresistive RAM to create a new logic-in-memory architecture, Chapter 61 (Varga et al.) implements a full-adder circuit in NML, Chapter 62 (Breitkreutz et al.) models a simple NML 1-bit adder with irradiation reduced switching levels, and in Chapter 63, Pulecio et al. present an alternative concept of magnetic fieldbased computing with an image processing example.
In the last section, the remaining chapters (except for one) deal with spintronics. Chapter 64 (Rakheja and Naeemi) confronts the interconnection challenges facing all-spin logic and considers the possibilities for graphene interconnect. In Chapter 65, Wan et al. consider the impact of scattering centers on conductance anomalies in spin contacts, and Wijesundara and Stinaff look for electron-spin control mechanisms in quantum-dot molecules, which are candidates for quantum computing systems, in Chapter 66. In Chapter 67, Munira et al. close out the spintronics section with an examination of memory materials.
In closing with Chapter 68, Blom and Stokbro call for a new generation of simulation tools to handle nanoscale mechanisms in realistic nanodevice geometries.
We hope you enjoy the book, and that it serves as a continuing reference and source of ideas for years to come.
James E. Morris
Portland, Oregon
Krzysztof Iniewski
Vancouver, British Columbia, Canada