Carbon nanotubes as building blocks of quantum dots

Quantum dots have been fabricated with single-wall carbon nanotubes (SWCNTs), and their transport properties have been measured at low temperatures. The single-electron transport measurements revealed the artificial atom characteristics with a shell structure and the Zeeman splitting of single particle states. They have been observed with the metallic SWCNT that includes many electrons, in striking contrast to the case of semiconductor artificial atoms that have a few electrons. The unique features in the SWCNT artificial atom are discussed in terms of the energy scales associated with the quantum dot.     

Possible observation of coulomb blockade at room temperature

We have studied the (I–V) characteristics of the tunnel junction formed between the tip and the substrate in an STM at room temperature. We find that in such an arrangement it may be possible to get a junction capacitance ⋍10⁻¹⁹ F and junction conductance <1μs. When the junction conductance is <1μs strong nonlinearity is observed in the (I–V) characteristics. We explain this nonlinearity as onset of coulomb blockade of tunneling electrons.     

单电子晶体管及其工艺制作技术

基于库仑阻塞效应和量子尺寸效应工作的单电子晶体管(SET)由于具有超小器件尺寸、超低功耗、超低工作电流和超高工作频率等特点,受到人们的重视和深入研究。本文通过简要介绍SET的器件结构、原理和特性,分析了实现SET的关键因素,回顾和评述了SET制作技术的进展及前景。     

基于Creator/Vega Prime的区域封锁作战系统

基于Multigen Creator/Vega Prime软件开发了子弹药封锁区域协同作战仿真系统;针对在作战区域实行封锁并打击封锁区域的敌方装备和有生力量进行了研究,实现延误敌方战机,减缓其兵力集结和部署,掌握战时主动的目的;主要通过围绕实体建模、模型驱动、碰撞检测、粒子特效等关键技术;综上所述,为实现对敌方飞机进行封锁区域协同打击的可视化仿真,重点研究了Creator和基于VC++的Vega Prime的视景仿真控制的过程和方法;研究结果表明,对子弹药区域封锁作战的实时仿真具有一定的参考价值。     

Effect of electromagnetic environment effect on coherent and incoherent Cooper pair tunneling in superconducting C-SET

Cooper pair tunneling in voltage-biased superconducting C-SET structure is discussed with emphasis on the electromagnetic environment effect based on the self-consistent microscopic theory of Coulomb blockade in C-SET. It is shown that coherent Cooper pair tunneling survives only in the low impedance limit where charge fluctuation is large, while incoherent Cooper pair tunneling survives in both low- and high-impedance limits.     

半导体量子电子和光电子器件

本文阐述了半导体异质结构电子的量子特性 ,如电子波输运、库仑阻塞效应等。介绍了几种新颖、典型的量子电子器件和量子光电子器件的物理模型和基本原理。这些器件包括了单电子晶体管、共振隧穿二极管、高电子迁移率晶体管、δ掺杂场效应晶体管、量子点元胞自动机、量子阱红外探测器、埋沟异质结半导体激光器、量子级联激光器等。给出了作者在半导体量子器件物理方面的最新研究结果。     

单岛单电子晶体管的电导分析

基于单电子经典理论,本文通过分析得出了单岛单电子晶体管的源漏电导模型,并对其进行了详细的分析讨论.单岛单电子晶体管的源漏电导随着源漏电压的变化发生周期性的振荡衰减,并随着源漏电压的增大逐渐收敛于本征电导值.源漏电导的这种特性受温度、结电阻、结电容等参数的影响.分析结果表明,源漏电导分析模型对单电子晶体管的大规模应用具有非常重要的意义. 关键词： 单电子晶体管 电导 库仑振荡 库仑阻塞     

Effect of gold electrode crystallographic orientations on charge transport through aromatic molecular junctions

ABSTRACT

We examined the electrical conduction through single-molecular junctions comprising of anthracenedithiol molecule coupled to two gold electrodes having ?1,0,1?, ?1,1,0? and ?1,1,1? crystallographic orientations. Owing to this jellium model, we evaluated the values of current and conductance using non-equilibrium Green's functions combined with extended Huckel theory. This data was further interpreted in terms of transmission spectra, density of states and their molecular orbital analysis for zero bias. We evinced the oscillating conductance in all three cases, due to the oscillation of orbital energy relative to Fermi level. Our detailed analysis suggested that electrode orientation can tune the molecule–electrode coupling and hence conduction. Anthracene molecular junction with ?1,1,0? orientation displayed favourable conduction, when compared to the other two orientations, thus can provide us an insight while designing futuristic molecular electronic devices.     

Power output and efficiency of quantum dot attached to ferromagnetic electrodes with non-collinear magnetic moments

Non-linear charge and heat transport through a single-level quantum dot in the Coulomb blockade regime is investigated within the framework of non-equilibrium Green function formalism and power output and efficiency of the device are studied. It is found that maximum power as well as efficiency depends on the relative orientation of magnetic moments in electrodes and can vary with polarization factor p. In general, power output is suppressed in magnetic systems and decreases with polarization. The highest efficiency can be attained in antiparallel configuration, and moreover, it does not depend on p. Spin power as well as spin efficiency of the system is introduced and discussed. It is also shown that in the Coulomb blockade regime the (spin) efficiency of the device operating under maximum power conditions varies with temperature bias in a non-monotonic way and shows a flat maximum for low ΔT.     

硅基单电子晶体管的可控制备

采用电子束曝光、感应耦合等离子体刻蚀和热氧化等工艺技术,通过独特的图形反转设计,即在电子束曝光时采用负的曝光图形,并以电子束曝光的光刻胶作为掩膜进行干法刻蚀,通过后续的干法热氧化等工艺,在磷离子重掺杂的绝缘体上硅基底上成功地制备出单电子晶体管。该方法具有高精度、结构可控、可重复和加工成本低的优点,可作为一种批量制备单电子晶体管的工艺技术。所制备的单电子晶体管在2.6 K到100 K的温度范围内呈现出明显的库仑阻塞效应,导通电阻小于100 kΩ。该单电子晶体管将成为高速、高灵敏度射频电路的关键器件。