Effect of the Electrodynamic Environment on Electrical Transport in Nanoscale Structures

电动力环境对纳米结构电传输的影响

• 批准号: 9974365
• 负责人: Alexander Rimberg
• 金额: --
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9974365&HistoricalAwards=false
• 关键词: Effect; Electrodynamic; Environment; Electrical; Transport

9974365RimbergThis project focuses on the investigation of the tunneling process in the presence of a tunable source of radiation. In many nanoscale systems, quantum mechanical tunneling is a fundamentally important process in electrical transport. In condensed matter systems, when considering tunneling attention must be paid not only to the electrons (or other particles) which are themselves tunneling, but also the electromagnetic environment to which they are coupled. In many cases the environment is fixed and not well characterized. In this project a model system consisting of a tunneling structure coupled to a tunable environment has been fabricated. The system consists of an Al/AlOx single-electron transistor (SET) coupled to a quantum dot in a GaAs/AlGaAs heterostructure. The Al/AlOx tunnel junctions form nearly ideal tunneling elements due to their high barriers and lack of defects. The quantum dot forms an extremely flexible environment, since its impedance and energy level structure are tunable over a physically interesting range. By measuring the dc I-V characteristics of the SET as the degree of confinement of the quantum dot is varied, one is able to observe how changes in the environment affect transport through the SET. Furthermore, since the SET I-V characteristics are naturally sensitive to the impedance of the environment and to frequencies eV/h where V is the applied voltage, one may also obtain information about the impedance of the dot at frequencies in the gigahertz range. The research in this project will also serve as an opportunity for students, both graduate and undergraduate, as well as post doctoral research associates to acquire state-of-the-art experimental skills in an area of great technological importance during the next few decades of the 21st Century.%%% In many very small physical systems (ones which measure only a few tens of billionths of a meter on a side), electrons facing a barrier can "tunnel" through the barrier instead of going over it. This kind of process is the dominant form of electrical conduction in many tiny structures. The environment surrounding an electron, including the presence of other electrons or of vibrations, can affect its ability to tunnel. In many cases, however, it is unclear what in the environment is affecting the tunneling, and it is usually impossible to change it. This research proposes to use two specialized devices to approach this problem. One, known as a single electron transistor, allows great control over tunneling; in fact electrons in this device can be used to tunnel one at a time. The second device, known as a quantum dot, consists of a small number (only a few hundred) of electrons confined in a very small area by energy barriers. By controlling the height of the barriers it is possible to control how easy or difficult it is for electrons to enter or leave the dot. This variability will allow the dot to serve as an artificial environment that is well understood and tunable. By fabricating the single electron transistor very close to the dot, one is able to observe how changes in the dot affect the tunneling in the transistor. The goal of this research is then to obtain a clearer understanding of how electrical conduction works in extremely small structures and thereby guide further advances in the technological realization of quantum structures in subnano-technology. Undergraduate and graduate students, as well as post doctoral research associates will participate in this research. They will thereby acquire state-of -the-art skills that will prepare them for employment in forefront areas of science and technology during the 21st Century.

9974365Rimberg 该项目重点研究存在可调辐射源的情况下的隧道掘进过程。在许多纳米级系统中，量子力学隧道效应是电传输中一个极其重要的过程。 在凝聚态物质系统中，在考虑隧道效应时，不仅要注意隧道效应的电子（或其他粒子），还要注意它们耦合的电磁环境。 在许多情况下，环境是固定的并且没有很好地表征。 在该项目中，制造了一个由与可调环境耦合的隧道结构组成的模型系统。 该系统由与 GaAs/AlGaAs 异质结构中的量子点耦合的 Al/AlOx 单电子晶体管 (SET) 组成。 Al/AlOx 隧道结由于其高势垒且无缺陷，形成近乎理想的隧道元件。量子点形成了一个极其灵活的环境，因为它的阻抗和能级结构可以在物理上有趣的范围内调节。 当量子点的限制程度变化时，通过测量 SET 的直流 I-V 特性，人们能够观察环境的变化如何影响通过 SET 的传输。 此外，由于SET I-V特性自然对环境阻抗和频率eV/h敏感，其中V是施加的电压，因此人们还可以获得关于在千兆赫范围内的频率下的点的阻抗的信息。 该项目的研究还将为研究生和本科生以及博士后研究员提供一个机会，让他们在未来几十年内获得具有重大技术重要性的领域的最先进的实验技能。 21 世纪。%%% 在许多非常小的物理系统（边长仅为几十亿分之一米的系统）中，面对势垒的电子可以“隧道”穿过势垒，而不是越过它。 这种过程是许多微小结构中导电的主要形式。 电子周围的环境，包括其他电子或振动的存在，会影响其隧道能力。 然而，在许多情况下，尚不清楚环境中的什么因素正在影响隧道效应，而且通常不可能改变它。 这项研究建议使用两种专用设备来解决这个问题。 其中一种被称为单电子晶体管，可以很好地控制隧道效应；事实上，该装置中的电子可用于一次隧道传输一个电子。 第二种设备称为量子点，由少量（仅几百）电子组成，这些电子被能垒限制在非常小的区域内。 通过控制势垒的高度，可以控制电子进入或离开点的难易程度。这种可变性将使点成为一个易于理解和可调的人工环境。 通过在非常靠近点的位置制造单电子晶体管，人们能够观察点的变化如何影响晶体管中的隧道效应。 这项研究的目标是更清楚地了解导电如何在极小的结构中工作，从而指导亚纳米技术中量子结构的技术实现的进一步进展。 本科生和研究生以及博士后研究员将参与这项研究。 他们将由此获得最先进的技能，为 21 世纪科技前沿领域的就业做好准备。