Single-electron transistors based on gate-induced Si island for single-electron logic application

The island size dependence of the capacitance components of single-electron transistors (SETs) based on gate-induced Si islands was extracted from the electrical characteristics. In the fabricated SETs, the sidewall gate tunes the electrically induced tunnel junctions, and controls the phase of the Coulomb oscillation. The capacitance between the sidewall gate and the Si island extracted from the Coulomb oscillation phase shift of the SETs with sidewall depletion gates on a silicon-on-insulator nanowire was independent of the Si island size, which is consistent with the device structure. The Coulomb oscillation phase shift of the fabricated SETs has the potential for a complementary operation. As a possible application to single-electron logic, the complementary single-electron inverter and binary decision diagram operation on the basis of the Coulomb oscillation phase shift and the tunable tunnel junctions were demonstrated.     

A single-electron transistor model based on a numerical solution of the poisson equation

A numerical model of a single-electron metal transistor is proposed based on a solution of the Poisson equation. The model provides a good agreement with experimental data on the current-voltage characteristics obtained at nonzero temperatures in the ambient medium.     

An investigation into the feasibility of myoglobin-based single-electron transistors

Myoglobin single-electron transistors were investigated using nanometer-gap platinum electrodes fabricated by electromigration at cryogenic temperatures. Apomyoglobin (myoglobin without the heme group) was used as a reference. The results suggest single-electron transport is mediated by resonant tunneling with the electronic and vibrational levels of the heme group in a single protein. They also represent a proof-of-principle that proteins with redox centers across nanometer-gap electrodes can be utilized to fabricate single-electron transistors. The protein orientation and conformation may significantly affect the conductance of these devices. Future improvements in device reproducibility and yield will require control of these factors.     

Effects of oxidation process on the tunneling barrier structures in room-temperature operating silicon single-electron transistors

We investigate the tunneling barrier structures in the room-temperature operating silicon single-electron transistors (SETs). The devices are fabricated in the form of the point-contact channel metal-oxide-semiconductor field-effect transistors with gate oxide formed by thermal oxidation or low-pressure chemical vapor deposition (LP-CVD). From the gate voltage and temperature dependence of the peak current in the SET characteristics, it is found that the thermal oxidation process leads to higher and narrower tunneling barriers. In some SETs with CVD-deposited gate oxide, thermally activated conduction over the low tunneling barriers is clearly observed in a wide temperature range from 100 K-300 K.     

基于岩石物理测试模型的测井曲线校正方法

针对密度测井、纵波速度和横波速度曲线探测深度较浅，受井眼不规则影响比较严重的问题，为研究储层各属性的影响及与弹性属性间的关系，采用岩石物理模型对测井资料进行诊断和校正，提高测井曲线与地层信息的匹配程度。结果表明：经过岩石物理模型诊断和校正的测井资料能明显的提高测井资料的品质，根据校正后的资料才能正确的标定井震之间的关系，为地震解释和反演提供可靠的依据。     

New adders using hybrid circuit consisting of three-gate single-electron transistors (TG-SETs) and MOSFETs

A half-adder (HA) and a full-adder (FA) using hybrid circuits combining three-gate single-electron transistors (TG-SETs) with metal-oxide-semiconductor field-effect-transistors (MOSFETs) are proposed. The proposed HA consists of three TG-SETs, two enhanced-mode NMOSFETs, and two depletion-mode NMOSFETs, and the proposed FA consists of eight TG-SETs, two enhanced-mode NMOSFETs, and two depletion-mode NMOSFETs. The complexities in the HA and the FA are 7 and 12, respectively, and the worst-case delays in the HA and the FA are 1.48 ns and 2.25 ns, respectively. Compared with the conventional CMOS FA with 0.35 microm technology, the proposed FA can be constructed with 0.43 of devices, and can operate with 3.5 of worst-case delay, 1/534 of average power consumption, and 1/152 of power-delay-product (PDP). The proposed HA and FA can be operated as a half-subtractor (HS) and a full-subtractor (FS) in the case when the levels of the control gates in the HA and the FA are fitly determined. The basic operations of the proposed HA and the proposed FA have been successfully confirmed through SPICE circuit simulation based on the physical device model of TG-SETs.     

表面声波单电子输运器件中弱电流的测量

研究表面声波单电子输运(SAW/SET)器件中的量子化声电电流对于揭示表面声波驱动的单电子输运特性有重要意义,并且有可能应用于量子电流基准,从而把安培与基本电荷和频率联系起来.为此设计了一种高精度高智能测量系统用于测量表面声波单电子输运器件中的声电电流.通过采用高性能Ⅰ-Ⅴ转换器和小波去噪等措施,使系统的噪声峰峰值小于30fA;采用LabVIEW编写的测量程序和合适的硬件实现了智能化的自动测量.该系统已成功地应用到SAW/SET器件中弱电流的测量,为将来揭示表面声波驱动的单电子输运特性和量子电流基准的可能实现做了有益的探索.     

表面声波单电子输运器件中弱电流的测量

研究表面声波单电子输运（SAW/SET）器件中的量子化声电电流对于揭示表面声波驱动的单电子输运特性有重要意义,并且有可能应用于最子电流基准,从而把安培与基本电荷和频率联系起来。为此设计了一种高精度高智能测量系统用于测量表面声波单电子输运器件中的声电电流。通过采用高性能I—V转换器和小波去噪等措施,使系统的噪声峰峰值小于30fA;采用LabVIEW编写的测量程序和合适的硬件实现了智能化的自动测量。该系统已成功地应用到SAW／SET器件中弱电流的测量,为将来揭示表面声波驱动的单电子输运特性和量子电流基准的可能实现做了有益的探索。     

A radio frequency single-electron transistor based on an InAs/InP heterostructure nanowire

We demonstrate radio frequency single-electron transistors fabricated from epitaxially grown InAs/InP heterostructure nanowires. Two sets of double-barrier wires with different barrier thicknesses were grown. The wires were suspended 15 nm above a metal gate electrode. Electrical measurements on a high-resistance nanowire showed regularly spaced Coulomb oscillations at a gate voltage from -0.5 to at least 1.8 V. The charge sensitivity was measured to 32 microe rms Hz(-1/2) at 1.5 K. A low-resistance single-electron transistor showed regularly spaced oscillations only in a small gate-voltage region just before carrier depletion. This device had a charge sensitivity of 2.5 microe rms Hz(-1/2). At low frequencies this device showed a typical 1/f noise behavior, with a level extrapolated to 300 microe rms Hz(-1/2) at 10 Hz.     

An overview of ion sputtering physics and practical implications

The first part of this review surveys the forms of energy exchange between incident ions and target atoms, going on to an examination of the distribution in depth of deposited energy. This analysis is then used to interpret the sputtering yield under various circumstances. The last part of the paper is devoted to a survey of different forms of radiation damage in sputtered targets, with special reference to the many factors that modify the original composition profile: such modification is related to the bombardment conditions used in analytical techniques such as AES, ESCA or SIMS which may be used,inter alia, to determine composition profiles.     

The effect of irradiation on the characteristics of MOS transistors

We have experimentally studied the effect of X-ray radiation on the parameters of MOS transistors. An analysis showed that correct evaluation of the density of surface states and the gate insulator charging by method of subthreshold current-voltage characteristics requires taking into account the planar inhomogeneity of a transistor. Some complication of the method is compensated by the increasing accuracy of determination of the surface parameters and the additional possibility of determining fluctuations of the surface potential.     

A numerical study on the mechanical characteristics of zinc oxide-based transparent thin film transistors

Zinc Oxide (ZnO) based Thin Film Transistors (TFTs) have been fabricated and analyzed to investigate mechanical characteristics regarding the stress, strain and deformation of electro circuits using the Finite Element Method (FEM). As the best compromise between the stretching and bending abilities, the coating thickness of SU-8 can be as important for bendability as a neutral mechanical plane. The neutral mechanical plane in electro circuits was designed for obtaining flexibility, e.g., bendability, in a previous numerical study. After that, through experimental validation, we observed what degree of SU-8 thickness was attributable for improved mechanical stability. The results suggest that not only numerical but also experimental measurements of the deformation and SU-8 coating thickness in electro circuits are useful for enhancing structural stability.     

Brief note—A criterion for unstable elastic-plastic brittle fracture based on more realistic model under plane stress

A criterion for unstable elastic-plastic brittle fracture under plane stress was previously proposed based on energy balance considerations, in which the plastic work term was used based on Dugdale model of plastic zone pattern. The realistic pattern, however, of the plastic zone is far from a Dugdale model. Therefore, in this article, a more realistic pattern is used.As a result, a more realistic criterion for unstable elastic-plastic brittle fracture has been obtained. In this new criterion, +p appears in place of the material surface energy term in the previous criterion, where p is the plastic work term corresponding to the excess plastic zone pattern extending in the direction perpendicular to the crack propagation direction beyond over the boundary of Dugdale model.

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Zusammenfassung Man hatte eine Kennzeichnung für den unstabilen elasto-plastischen Sprödbruch unter planer Beanspruchung vorgeschlagen, welche auf Energiebilanzüberlegungen beruhte, wobei das die plastische Arbeit beschreibende Glied auf dem Dugdale-Modell für plastische Verformungszonen begründet war.Der wirkliche Vorgang im plastischen Bereich ist jedoch weft vom Dugdale-Modell entferm. Deshalb wird im vorliegenden Bericht von realistischeren Vorstellungen ausgegangen.Hierbei ergibt sich eine wirklichkeitsgetreuere Kennzeichnung des unstabilen elasto-plastischen Sprödbruchs. In diesem neuen Ausdruck erscheint die Summe +p an Stelle der Materialoberflächenenergie y in dem früheren Kriterium, wobei p die plastische Verformungsarbeit für die plastischen Bereiche darstellt, welche senkrecht zur RiBfortpflanzungsrichtung, jenseits der vom Dugdale-Modell vorgesehenen Grenze liegen.

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Résumé On a précédemment proposé un critère, basé sur des considérations d'équilibre énergétique, pour la rupture fragile en conditions élasto-plastique et sous état plan de tension. Dans ce critère, on faisait appel au travail plastique, sur la base du modèle du Dugdale relatif aux configurations des zones de déformation plastique.La configuration réelle de ces zones est, toutefois, assez différente de celle du modèle de Dugdale. On a donc consideré, dans ce mémoire, une configuration plus réaliste.On a ainsi obtenu un critere, plus réaliste, de la rupture fragile élasto-plastique. Dans celui-ci,l'ènergie de surface du précédent critère a été remplacé par un terme +p, où p représente le travail de déformation plastique correspondant aux zones plastiques qui s'étendent, perpendiculairement à l'axe de propagation de la fissure, au-delà de la limite prévue par Dugdale.

     

A method to model realistic particle shape and inertia in DEM

A simple and fast original method to create irregular particle shapes for the discrete element method using overlapping spheres is described. The effects of its parameters on the resolution of the particle shape are discussed. Overlapping spheres induce a non-uniform density inside the particle leading to incorrect moments of inertia and therefore rotational behaviour. A simple method to reduce the error in the principal moments of inertia which acts on the individual densities of the spheres is also described. The pertinence of the density correction is illustrated by the case of free falling ballast particles forming a heap on a flat surface. In addition to improve behaviour, the correction reduces also computational time. The model is then used to analyse the interaction between ballast and geogrid by simulating pull-out tests. The pulling force results show that the model apprehends better the ballast geogrid interlocking than models with simple representation of the shape of the particles. It points out the importance of modelling accurately the shape of particles in discrete element simulations.     

Field-effect transistors of the block co-oligomers based on thiophene and pyridine

We have investigated the structural and electrical characteristics of two kinds of block co-oligomers, 5,5″-Bis(2-pyridyl)-2,2′:5′,2″-terthiophene (5A) and 2,5-Bis(2-(2′-thienyl)-pyridine-5-yl)thiophene (5B), which are composed of electron-donating thiophene and electron-withdrawing pyridine rings. At the view of building block units, the amount of the module units included in these molecules is completely equivalent to each other. X-ray diffraction patterns of 5A and 5B thin films grown on atomically flat α-Al₂O₃ (0001) substrates indicated a high degree of orientation along the c-axis. Field-effect transistors (FETs) of 5A and 5B thin films were fabricated and evaluated without exposure to air. The FETs based on 5A active layers exhibited p-type behavior with a mobility of ~ 10⁻³ cm²/V·s and an on-off ratio of 10⁴, while no switching behavior was observed in FETs based on 5B active layers. The lower highest occupied molecular orbital (HOMO) of 5B than that of 5A in the quantum-chemical calculation might explain these FET behaviors. Thus, HOMO, lowest unoccupied molecular orbital (LUMO) levels and FET actions of the co-oligomer molecules that consist of the same amount of building blocks can be controlled by the sequence of electron-donating and electron-withdrawing building blocks.     

A novel contact engineering method for transistors based on two-dimensional materials

Contact engineering is of critical importance for two-dimensional (2D) transition metal dichalcogenide(TMD)-based devices. However, there are only a few solutions to overcome this obstacle because of the complexity of the TMD-contact interface. In this work, we propose a novel method using a soft plasma treatment followed by the seamless deposition of a metal electrode to reduce the contact resistance of MoS_2 field effect transistors(FETs). The treated FETs exhibit three times higher mobility than the control FETs without plasma treatment. The soft plasma treatment can remove the facial sulfur atoms and expose the middle Mo atoms so that they come into direct contact with the metal electrode, thus greatly improving the contact behavior. First-principles calculation is also performed to support the experimental results. Our potentially scalable strategy can be extended to the whole family of TMD based FETs to provide a possible route of device processsing technology for 2D device application.     

Effect of measuring environment on the electrical characteristics of NiPc based thin film transistors: The effects of ozone

Electrical characteristics of Organic Thin Film Transistors (OTFT) are found to be sensitive to ambient atmosphere. The electrical properties of Metal-Phthalocyanines (M-Pc) are affected upon exposure to an atmosphere containing oxidizing molecules like oxygen, nitrogen oxides or ozone. This phenomenon finds application in the use of OTFT based on nickel-phthalocyanine (NiPc) as gas sensors. In this work, tests of ozone detecting were carried out exhibiting a high sensitivity to ozone. The observed changes in the electrical characteristics, when the OTFT is exposed to an ambient atmosphere, are discussed in terms of ozone doping process. Our results show that NiPc-based OTFTs can represent a new class of ozone sensors.     

物理学对现代表面技术的支撑作用

从真空技术、等离子体技术、激光技术等表面技术发展的几个方面论述了电学、磁学、光学等物理学知识在表面技术中的广泛应用以及对表面处理技术科学的巨大推动作用.指出,物理学的进步对表面技术的进步有着非常重要的支撑作用.