单电子物理学

单电子晶体管是几年前才发现的一种功能奇特的新型器件。围绕着这种器件工作机理的研究，逐渐发展了一门以库仑抑制模型为核心的崭新学科──单电子物理学。本文以单电子晶体管的发展为线索，介绍单电子物理学的主要内容及其研究现状。     

Consideration of the “island” background charge in single-electron transistor simulation

Three approximations of the “island” background charge are described within the proposed 2D numerical model of the metal single-electron transistor. These approximations fit the experimental data well when calculating I–V characteristics of single-electron transistors according to the model developed in many cases. The validity of these approximations is exemplified by specific calculations of I–V characteristics.     

基于主方程法单电子晶体管的Verilog-A行为模型

 基于单电子晶体管的主方程算法,在简化Lientschnig的单电子晶体管模型基础上,建立了基于Verilog-A的单电子晶体管行为描述模型,并利用Cadence Spectre 仿真器对该模型进行了验证.通过单电子晶体管逻辑电路的设计和仿真,表明该模型具有合理的精确度,且速度快,为单电子晶体管电路及混合电路的仿真提供了一种有效的方法.     

单电子加法器的Monte Carlo模拟

建立了一个单电子加法器的物理模型,采用Monte Carlo法对其进行数值模拟,分析了温度、栅极电容及隧道结电容等参数对单电子加法器的电学特性的影响。发现加法器对温度和栅极电容器的电容变化非常敏感,而改变隧道结的电容、电阻对单电子加法器的电学特性的影响不明显。     

单电子晶体管及其在细胞神经网络中的应用

研究了单电子晶体管的特性及主方程法,建立了基于主方程法的单电子晶体管SPICE模型,实现了对细胞神经网络单元的仿真。仿真结果表明,采用主方程法建立的单电子晶体管模型具有合理的精确度,对细胞神经网络单元的实现具有速度快、低功耗的优点,适合复杂细胞神经网络的进一步构建。     

Low-Frequency Noise Phenomena in Switched MOSFETs

In small-area MOSFETs widely used in analog and RF circuit design, low-frequency (LF) noise behavior is increasingly dominated by single-electron effects. In this paper, the authors review the limitations of current compact noise models which do not model such single-electron effects. The authors present measurement results that illustrate typical LF noise behavior in small-area MOSFETs, and a model based on Shockley-Read-Hall statistics to explain the behavior. Finally, the authors treat practical examples that illustrate the relevance of these effects to analog circuit design. To the analog circuit designer, awareness of these single-electron noise phenomena is crucial if optimal circuits are to be designed, especially since the effects can aid in low-noise circuit design if used properly, while they may be detrimental to performance if inadvertently applied     

Design and simulation of a nanoelectronic single electron 2-4 decoder using a novel simulator

The design and simulation of a single-electron 2-4 decoder using a novel single electron circuit simulation tool named single-electron circuit simulator (SECS), is presented in this paper. In single electron circuits bits of information are represented by the presence or absence of single electrons at conducting or semiconducting islands. SECS utilizes the Monte Carlo method and the change in free-energy of the whole circuit determines the tunnel rates of possible tunnel events, providing thus a real time simulation of any arbitrary single-electron circuit. Furthermore, SECS is using the SPICE interface for schematic capture. SPICE models of single-electron circuit structures have been developed and, therefore, SECS can also be used for the design and simulation of hybrid microelectronic—single-electron circuits.     

Analog Computation Using Single-Electron Circuits

Analog computation is a processing method that solves a given problem by utilizing an analogy of a physical system to the problem. An idea is presented here for relating the behavior of single-electron circuits to analog computation. As an instance, a method is proposed for solving a combinatorial problem, the three-colorability problem, by using the properties of single-electron circuits. In problem solving, a single-electron circuit is constructed that is analogous to a given problem; then, through an annealing procedure, the circuit is made to settle down to its minimun energy state. The correct solution to the problem can be obtained by checking the final arrangement of electrons in the circuit. Analog computation is a promising architecture for single-electron computing systems.     

单电子存储器

介绍了单电子存储器的发展情况和几种单电子存储器的基本特性,并将库仑阻塞效应作为存储器工作的理论基础进行了讨论。随着传统存储器集成度的不断提高,每个存储单元的电子数目不断减少,并逐渐接近其极限,使传统存储器的发展面临困难。采用单电子存储器有望解决这个困难,它们通常具有单个量子点或者是多隧穿结结构,存储一个比特的信息只需要精确控制增加或者减少一定数目的电子就可以实现。单电子器件的工作通常只需要很少的电子甚至一个电子就可以实现,具有高速和低功耗的特点,因此可以实现信息超高密度存储。与单电子逻辑电路相比,单电子存储器更容易解决随机背景电荷涨落的问题,因此从实际应用的角度来看,单电子存储器的应用前景更为光明。     

Design, simulation and performance evaluation of a single-electron 2-4 decoder

In this paper, we present a single-electron 2-4 decoder built using single-electron devices. The circuit is designed using a proper tool based on a Monte Carlo technique. First a single-electron AND gate is studied and then the 2-D decoder circuit is designed and studied. The results proved that the circuit was a 2-4 decoder, while the behaviour of the free energy of the system (which was calculated to be 4.90×10⁻¹ eV) and the stability diagram verified the correct functioning of the circuit.     

单电子晶体管I-V特性数学建模

基于正统单电子理论，提出了单电子晶体管的I-V特性数学模型。该模型的优点是：它由实际物理参数直接获得；支持双栅极工作，更利于逻辑电路应用。I-V特性和跨导仿真结果证实了它的准确性。     

单电子晶体管的I-V特性数学模型及逻辑应用

基于正统单电子理论，提出了单电子晶体管的I-V特性数学算法改进模型。该模型的优点是：考虑了背景电荷的影响，可由实际物理参数直接获得，支持双栅极工作，便于逻辑电路的分析。研究了背景电荷和各物理参数对I-V特性及跨导的影响，讨论了双栅极单电子晶体管的逻辑应用：简化了“异或”逻辑电路，改进了二叉判别图电路的逻辑单元。     

A two-dimensional numerical model of a single-electron transistor

A two-dimensional numerical model of a single-electron transistor is suggested. It is based on the numerical solution to Poisson’s equation and makes it possible to calculate a potential distribution and currentvoltage characteristics (CVCs) of the transistor in dependence of its design, process, and electrophysical parameters. Model results agree well with experimental data.     

Electrical characteristics and modelling of multi-island single-electron transistor using SIMON simulator

In this paper, we present a multi-island single-electron transistor (MISET) model based on the orthodox theory and solving the master equation. Using SIMON simulator, we investigate the electrical characteristics of single-electron transistors (SETs) based on multiple islands and show the temperature dependence of the Coulomb oscillation of the SET with one to six islands as a function of gate voltage V_g in the temperature range from T=5 to 50 K. Values of current tend to increase proportionally with temperature. For a high drain voltage, the MISET behaved as a single-island device. This is probably because the multiple islands were electrically enlarged and merged into a single island owing to the high applied drain voltage. Finally, we compare the advantages of MISET face to single-island SETs with identical dimensions of islands.     

集成化单电子器件研究进展

传统MOSFET结构正以较快的发展速度接近其物理极限,而单电子器件将成为新型的高性能集成化器件结构。本文采用量子点及其库伦阻塞效应等概念对单电子器件的工作原理进行了系统分析,并介绍了单电子器件在存储器和高灵敏度静电计方面的应用,最后指出了单电子器件的新发展方向及所面临的问题。     

Characteristics of multiple-island single-electron chains in relation to various factors

The characteristics of multiple-island single-electron chains are analyzed theoretically in relation to the design parameters, the materials, the background charge, and the environmental temperature with the aid of a model developed on the basis of the solution of the Poisson equation and the Monte Carlo method. It is shown that the main parameter which determines the temperature stability of the phenomenon of the Coulomb blockade is the potential-barrier height for tunneling junctions. The investigations of three systems of materials (Co-Al-O, Au-Al₂O₃, and Cr-Cr₂O₃) take shown that the multiple-island single-electron chains based on Co-Al-O are most preferable at the operating temperature. The chains based on Cr-Cr₂O₃ are less preferable.     

Dynamic exclusive-OR gate based on gate-induced Si islandsingle-electron transistor

Basic operation of a dynamic exclusive-OR gate implemented by a field effect transistor and a single-electron transistor is experimentally demonstrated, for the first time. Logic output voltage shows full swing operation at a supply voltage of 20 mV. Fabricated single-electron transistors are advantageous for implementing a multi-gate single-electron logic circuit     

Macromodeling of single-electron transistors for efficient circuitsimulation

In this study, the possibility of compact modeling in single-electron circuit simulation has been investigated. It is found that each Coulomb island in single-electron circuits can be treated independently when the interconnections between single-electron transistors are large enough and a quantitative criterion for this condition is given. It is also demonstrated that, in those situations, SPICE macromodeling of single-electron transistors can be used for efficient circuit simulation. The developed macromodel produces simulation results with reasonable accuracy and with orders of magnitude less CPU time than usual Monte Carlo simulations     

Single-electron random-number generator (RNG) for highly secure ubiquitous computing applications

Since the security of all modern cryptographic techniques relies on unpredictable and irreproducible digital keys generated by random-number generators (RNGs), the realization of high-quality RNG is essential for secure communications. In this report, a new RNG, which utilizes single-electron phenomena, is proposed. A room-temperature operating silicon single-electron transistor (SET) having nearby an electron pocket is used as a high-quality, ultra-small RNG. In the proposed RNG, stochastic single-electron capture/emission processes to/from the electron pocket are detected with high sensitivity by the SET, and result in giant random telegraphic signals (GRTS) on the SET current. It is experimentally demonstrated that the single-electron RNG generates extremely high-quality random digital sequences at room temperature, in spite of its simple configuration. Because of its small-size and low-power properties, the single-electron RNG is promising as a key nanoelectronic device for future ubiquitous computing systems with highly secure mobile communication capabilities.