Quantum Transport in Ultrasmall Devices

The operation of semiconductor devices depends upon the use of electrical potential barriers (such as gate depletion) in controlling the carrier densities (electrons and holes) and their transport. Although a successful device design is quite complicated and involves many aspects, the device engineering is mostly to devise a "best" device design by defIning optimal device structures and manipulating impurity profIles to obtain optimal control of the carrier flow through the device. This becomes increasingly diffIcult as the device scale becomes smaller and smaller. Since the introduction of integrated circuits, the number of individual transistors on a single chip has doubled approximately every three years. As the number of devices has grown, the critical dimension of the smallest feature, such as a gate length (which is related to the transport length defIning the channel), has consequently declined. The reduction of this design rule proceeds approximately by a factor of 1. 4 each generation, which means we will be using 0. 1-0. 15 ). lm rules for the 4 Gb chips a decade from now. If we continue this extrapolation, current technology will require 30 nm design rules, and a cell 3 2 size < 10 nm , for a 1Tb memory chip by the year 2020. New problems keep hindering the high-performance requirement. Well-known, but older, problems include hot carrier effects, short-channel effects, etc. A potential problem, which illustrates the need for quantum transport, is caused by impurity fluctuations.

Résumé
Proceedings of a NATO ASI held in Il Ciocco, Italy, July 17-30, 1994

Contenu
Lectures.- to Quantum Transport.- Traditional Modelling of Semiconductor Devices.- Quantum Confined Systems: Wells, Wires, and Dots.- Fabrication of Nanoscale Devices.- Artificial Impurities in Quantum Wires and Dots.- Mesoscopic DevicesWhat are They.- Trajectories in Quantum Transport.- Two-Dimensional Dynamics of Electrons Passing Through a Point Contact.- Localized Acoustic Phonons in Low Dimensional Structures.- Conductance in Quantum Boxes: Interference and Single Electron Effects.- Quantum Traffic Theory of Single Electron Transport in Nanostructures.- Some Recent Developments in Quantum Transport in Mesoscopic Structures and Quantum Wells.- Density Matrix Simulations of Semiconductor Devices.- Effects of Band-Structure and Electric Fields on Resonant Tunneling Dynamics.- Interacting and Coherent Time-Dependent Transport in Semiconductor Heterostructures.- Recursive Tight-Binding Green's Function Method: Application to Ballistic and Dissipative Transport in Semiconductor Nanostructures.- Screening and Many-Body Effects in Low-Dimensional Electron Systems.- Quantum Kinetics in Laser Pulse Excited Semiconductors.- Statistical Fluctuations in Devices.- Multiband and Multidimensional Analysis of Quantum Transport in Ultrasubmicron Devices.- Contributed Papers.- Vapor Etching of Beam-Deposited Carbon on Silicon Dioxide Films.- Electron Heating in GaAs due to Electron-Electron Interactions.- Transport and Optical Spectroscopy of an Array of Quantum Dots with Strong Coulomb Correlations.- Three-Dimensional Quantum Transport Simulations of Transmission Fluctuations in a Quantum Dot.- Acoustic Scattering of Electrons in a Narrow Quantum Well.- Non-Ohmic Phonon-Assisted Landauer Resistance.- Acoustic Phonon Relaxation in Valence Band Quantum Wells.- StationaryTransport of Holes in GaAs.- Beating Pattern in the Magneto-Oscillations of the 2DEG in Semiconductor Quantum Wells.- Ultrafast Coherent and Incoherent Dynamics in Photoexcited Semiconductors.- Theoretical Analysis of Terahertz-Emission from Asymmetric Double-Quantum Wells.- Carrier Transport in Quantum Well Lasers: A Comparison between Different Heterostructures.- Small Signal Differential Mobility of Planar Superlattice Miniband Transport and Negative Differential Conductance.- General Conditions for Stability in Bistable Electrical Devices with S- or Z-Shaped Current-Voltage Characteristics.- Quantum Hydrodynamics: Derivation and Classical Limit.- A Transfer-Matrix Approach to Photon-Assisted Tunneling through a Driven Double-Barrier Diode.- Dynamics of Resonant Tunneling Domains in Superlattices: A Discrete Drift Model.- Nonequilibrium Phenomena in Split Gate Quantum Waveguides.- Theory of Delta-Wires.- Model and Transport in a Three-Layered Heterostructure with Thin Quantum Wells in the Schottky Layer.- Dissipation Effects in Quantum Tunneling.- A First Step for Semiconductor Quantum Device Modeling with Incoherent Scattering.- Evaluation of the Mobility in a Si-SiO2 Inversion Layer at T=0 K Using Green's Function Formalism.- Linearized Quantum Transport Equations in Periodic Fields.- Photograph.- Participants.