Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> The physical phenomena which will ultimately limit MOS circuit miniaturization are considered. It is found that the minimum MOS transistor size is determined by gate oxide breakdown and drain-source punch-through. Other factors which limit device size are drain-substrate breakdown, drain ‘corner’ breakdown and substrate doping fluctuations. However these limitations are less severe than the oxide breakdown limitation mentioned above. Power dissipation and metal migration limit the frequency and/or packing density of fully dynamic and of complementary MOS circuits. In static non-complementary circuits, power dissipation is the principal limitation of the number of circuit functions per chip. The channel length of a minimum size MOS transistor is a factor of 10 smaller than that of the smallest present day devices. The tolerances required to manufacture such a transistor are compatible with electron beam masking techniques. It is thus possible to envision fully dynamic silicon chips with up to 10^7–10^8 MOS transistors per cm^2. <s> BIB001 </s> Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> Semiconductor Electronics. Silicon Technology. Metal--Semiconductor Contacts. pn Junctions. Currents in pn Junctions. Bipolar Transistors I: Basic Properties. Bipolar Transistors II: Limitations and Models. Properties of the Metal--Oxide--Silicon System. Mos Field--Effect Transistors I: Physical Effects and Models. Mos Field--Effect Transistors II: High--Field Effects. Answers to Selected Problems. Selected List of Symbols. Index. <s> BIB002 </s> Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> There are limits on the size and number of circuit elements that can be packed on a computer chip. One is the wave behavior of electrons, which can interfere with performance in the smallest of devices. Physicists are not turning that behavior to their advantage in a new kind of component that depends on electron waves for its operation. With the so called quantum semiconductor device, it will be possible to put the circuitry of a supercomputer on a single chip. The structures for quantum devices have already been made using the same materials as today's chips. Because they can be about 100 times smaller than the devices in present-day integrated circuits, designing and fabricating a viable device presents a formidable challenge. Manufacturing processes will have to become considerably more sophisticated, and new strategies for interconnection and architecture will have to be devised to cope with the special problems of size reduction. 5 figs. <s> BIB003 </s> Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> Introduction to the Physics of Gallium Arsenide Devices (H. Grubin) Modeling of GaAs and AlGaAs/GaAs Field Effect Transistors (M. Shur) Heterostructure Field Effect Transistors (S. Pei & N. Shah) Heterojunction Bipolar Transistor Technology (P. Asbeck, et al.) Resonant Tunneling Diodes and Transistors: Physics and Circuit Applications (S. Sen, et al.) JFET Technology (W. Geideman) Design of High-Speed GaAs MESFET Digital LSI Circuits (C. Chang) GaAs FET Amplifier and MMIC Design Techniques (T. Apel) GaAs Optoelectronic Device Technology (P. Yu & P. Chen) Electro-Optical Properties of Heterojunction and Quantum Well Structures of III-V Compound Semiconductors and Their Applications in Guided-Wave Devices (W. Chang) Quantum Mechanical Corrections to Classical Transport in Submicron/Ultrasubmicron Dimensions (M. Stroscio) Index. <s> BIB004 </s> Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> Electrons, bonds, bands and holes homogeneous semiconductor at equilibrium drift, diffusion, generation, recombination, trapping and tunneling metal-oxide-semiconductor capacitor P/N and other junction diodes metal-oxide-semiconductor and other field-effect transistors bipolar junction transistor and other bipolar transistor devices. <s> BIB005 </s> Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> The paper reviews the current state of molecular electronics and considers the most interesting trends in its development. It is noted that microscopic dimensions in quantum processes are not the only advantage of molecular technology. It is also important that chemical synthesis of molecular systems ensures the identity of assembled functional elements, thereby providing reliability and efficiency of quantum processes in molecular electronic devices. We propose using the quantum effect of the Peierls instability, which is readily realized in one-dimensional molecular systems. Advantages of this approach are discussed. <s> BIB006 </s> Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> (NOTE: Each chapter begins with an Introduction and concludes with a Summary, To Probe Further, and Exercises and Design Problems.) I. THE FABRICS. 1. Introduction. A Historical Perspective. Issues in Digital Integrated Circuit Design. Quality Metrics of a Digital Design. 2. The Manufacturing Process. The CMOS Manufacturing Process. Design Rules-The Contract between Designer and Process Engineer. Packaging Integrated Circuits. Perspective-Trends in Process Technology. 3. The Devices. The Diode. The MOS(FET) Transistor. A Word on Process Variations. Perspective: Technology Scaling. 4. The Wire. A First Glance. Interconnect Parameters-Capitance, Resistance, and Inductance. Electrical Wire Models. SPICE Wire Models. Perspective: A Look into the Future. II. A CIRCUIT PERSPECTIVE. 5. The CMOS Inverter. The Static CMOS Inverter-An Intuitive Perspective. Evaluating the Robustness of the CMOS Inverter: The Static Behavior. Performance of CMOS Inverter: The Dynamic Behavior. Power, Energy, and Energy-Delay. Perspective: Technology Scaling and Its Impact on the Inverter Metrics. 6. Designing Combinational Logic Gates in CMOS. Static CMOS Design. Dynamic CMOS Design. How to Choose a Logic Style? Perspective: Gate Design in the Ultra Deep-Submicron Era. 7. Designing Sequential Logic Circuits. Timing Metrics for Sequential Circuits. Classification of Memory Elements. Static Latches and Registers. Dynamic Latches and Registers. Pulse Registers. Sense-Amplifier Based Registers. Pipelining: An Approach to Optimize Sequential Circuits. Non-Bistable Sequential Circuits. Perspective: Choosing a Clocking Strategy. III. A SYSTEM PERSPECTIVE. 8. Implementation Strategies for Digital ICS. From Custom to Semicustom and Structured-Array Design Approaches. Custom Circuit Design. Cell-Based Design Methodology. Array-Based Implementation Approaches. Perspective-The Implementation Platform of the Future. 9. Coping with Interconnect. Capacitive Parasitics. Resistive Parasitics. Inductive Parasitics. Advanced Interconnect Techniques. Perspective: Networks-on-a-Chip. 10. Timing Issues in Digital Circuits. Timing Classification of Digital Systems. Synchronous Design-An In-Depth Perspective. Self-Timed Circuit Design. Synchronizers and Arbiters. Clock Synthesis and Synchronization Using a Phased-Locked Loop. Future Directions and Perspectives. 11. Designing Arithmetic Building Blocks. Datapaths in Digital Processor Architectures. The Adder. The Multiplier. The Shifter. Other Arithmetic Operators. Power and Spped Trade-Offs in Datapath Structures. Perspective: Design as a Trade-off. 12. Designing Memory and Array Structures. The Memory Core. Memory Peripheral Circuitry. Memory Reliability and Yield. Power Dissipation in Memories. Case Studies in Memory Design. Perspective: Semiconductor Memory Trends and Evolutions. Problem Solutions. Index. <s> BIB007 </s> Overview of Nanoelectronic Devices <s> I. INTRODUCTION <s> I. SEMICONDUCTOR FUNDAMENTALS. 1. Semiconductors -- A General Introduction. General Material Properties. Crystal Structure. Crystal Growth. 2. Carrier Modeling. The Quantization Concept. Semiconductor Models. Carrier Properties. State and Carrier Distributions. Equilibrium Carrier Concentrations. 3. Carrier Action. Drift. Diffusion. Recombination -- Generation. Equations of State. Supplemental Concepts. 4. Basics of Device Fabrication. Fabrication Processes. Device Fabrication Examples. R1. Part I Supplement and Review. Alternative/Supplemental Reading List. Figure Sources/Cited References. Review List of Terms. Part I Review Problem Sets and Answers. IIA. PN JUNCTION DIODES. 5. PN Junction Electrostatics. Preliminaries. Quantitative Electrostatic Relationships. 6. PN Junction Diode -- I-V Characteristics. The Ideal Diode Equation. Deviations from the Ideal. Special Considerations. 7. PN Junction Diode -- Small-Signal Admittance. Introduction. Reverse-Bias Junction Capacitance. Forward-Bias Diffusion Admittance. 8. PN Junction Diode -- Transient Response. Turn-Off Transient. Turn-On Transient. 9. Optoelectronic Diodes. Introduction. Photodiodes. Solar Cells. LEDs. IIB. BJTS AND OTHER JUNCTION DEVICES. 10. BJT Fundamentals. Terminology. Fabrication. Electrostatics. Introductory Operational Considerations. Performance Parameters. 11. BJT Static Characteristics. Ideal Transistor Analysis. Deviations from the Ideal. Modern BJT Structures. 12. BJT Dynamic Response Modeling. Equivalent Circuits. Transient (Switching) Response. 13. PNPN Devices. Silicon Controlled Rectifier (SCR). SCR Operational Theory. Practical Turn-on/Turn-off Considerations. Other PNPN Devices. 14. MS Contacts and Schottky Diodes. Ideal MS Contacts. Schottky Diode. Practical Contact Considerations. R2. Part II Supplement and Review. Alternative/Supplemental Reading List. Figure Sources/Cited References. Review List of Terms. Part II Review Problem Sets and Answers. III. FIELD EFFECT DEVICES. 15. Field Effect Introduction -- the J-FET and MESFET. General Introduction. J-FET. MESFET. 16. MOS Fundamentals. Ideal Structure Definition. Electrostatics -- Mostly Qualitative. Electrostatics -- Quantitative Formulation. Capacitance-Voltage Characteristics. 17. MOSFETs -- The Essentials. Qualitative Theory of Operation. Quantitative ID - VD Relationships. ac Response. 18. Nonideal MOS. Metal-Semiconductor Workfunction Difference. Oxide Charges. MOSFET Threshold Considerations. 19. Modern FET Structures. Small Dimension Effects. Select Structure Survey. R3. Part III Supplement and Review. Alternative/Supplemental Reading List. Figure Sources/Cited References. Review List of Terms. Part III Review Problem Sets and Answers. Appendix A. Elements of Quantum Mechanics. Appendix B. MOS Semiconductor Electrostatics -- Exact Solution. Appendix C. MOS C-V Supplement. Appendix D. MOS I-Vsupplement. Appendix E. List of Symbols. Appendix M. MATLAB Program Script. <s> BIB008
For the past 40 years, electronic computers have grown more powerful as their basic subunit, the transistor, has shrunk BIB002 . However, the laws of quantum mechanics and the limitations of fabrication techniques may soon prevent further reduction in the size of today's conventional fieldeffect transistors (FET's). Many investigators in the field of next-generation electronics project that during the next 10 to 15 years, as the smallest features on mass-produced transistors shrink from their present lengths of 250 nm to 100 nm and below, the devices will become more difficult and costly to fabricate. In addition, they may no longer function effectively in ultra-densely integrated electronic circuits  -  . (Note: 1 nm is 1 billionth of a meter, approximately 10 atomic diameters.) In order to continue the miniaturization of circuit elements down to the nanometer scale, perhaps even to the molecular scale, researchers are investigating several alternatives to the transistor for ultra-dense circuitry. These new nanometer-scale electronic (nanoelectronic) devices perform as both switches and amplifiers, just like today's transistors. However, unlike today's FET's, which operate based on the movement of masses of electrons in bulk matter, the new devices take advantage of quantum mechanical phenomena that emerge on the nanometer scale, including the discreteness of electrons. Manuscript received August 9, 1996 ; revised February 25, 1997 . This work was supported by a grant from The MITRE Corporation. The authors are with The MITRE Corporation, McLean, VA 22102 USA (e-mail: nanotech@MITRE.org). Publisher Item Identifier S 0018-9219(97)03635-9. What will such alternative next-generation nanodevices look like? Upon what operating principles will they function? How will they resemble present-day transistors, and how will they differ? This paper addresses these questions by surveying the literature about novel nanoelectronic devices that could replace the transistor in tomorrow's smaller, denser, and faster digital computers. The answers are presented in nonmathematical terms intended for a general, technically interested readership. However, this overview builds upon several earlier, more technical and specialized reviews BIB003 -  and treatises  - BIB004 , as well as the work of numerous research groups. Specifically, we will survey two broad classes of alternative nanoelectronic switches and amplifiers: • solid-state quantum-effect and single-electron devices; • molecular electronic devices. Devices in both classes take advantage of the various quantum effects that begin to dominate electron dynamics on the nanometer scale. Fabricating quantum-effect and single-electron devices in solids is the approach taken by most research groups exploring new-technology nanoelectronic devices  . It makes novel devices out of the same semiconductors used for transistors. Despite the novelty of the designs, researchers already have been able to develop, fabricate, and employ in circuitry several promising new device types by building upon 50 years of industrial experience with bulk semiconductors. Molecular electronics is a relatively new approach that would change both the operating principles and the materials used in electronic devices BIB006 ,  ,  -  . The incentive for such radical change is that molecules are naturally occurring nanometer-scale structures. Unlike nanostructures built from bulk solids, molecules can be made identically, cheaply, and easily, by the billions of trillions that will be needed for industrial-scale production of ultra-dense nanoelectronic computers. Two significant challenges are to devise molecular structures which act as electrical switches, and to assemble these molecules into the precise extended structures needed for reliable computation. Exciting theoretical and experimental progress toward these goals is just beginning. 0018-9219/97$10.00 © 1997 IEEE PROCEEDINGS OF THE IEEE, VOL. 85, NO. 4, APRIL 1997 To simplify the terminology, in focusing upon these two alternative types of nanoelectronic devices, we will not include nanometer-scale FET's in the category of "nanoelectronics." However, this work does not discount the important point of view that envisions the aggressive miniaturization of FET's down to the nanometer scale  , BIB001 - [41] . Rather, this work attempts to complement articles on that topic elsewhere in this issue of the Proceedings  , [171] . In so doing, this paper compares and contrasts the alternatives with FET's to arrive at a technology vision that is complementary to a vision of nanometer-scale circuitry based upon the continued miniaturization of FET's. Thus, before examining the designs for quantum-effect and single-electron nanoelectronic devices, we must examine the structure and function of conventional microelectronic transistors BIB007 , BIB005 , BIB008 , as well as their possible limitations.