Noise and High Frequency Properties of Single-Molecule Transistors

* 非技术摘要 * 晶体管是信息时代的基础。 在过去的60年里，晶体管已经从几厘米缩小到几十纳米，每个器件现在比人类头发的直径小1000多倍。 随着尺寸的进一步减小，量子效应在决定器件特性方面变得至关重要。 与此同时，获取有关设备的详细几何形状和材料质量的信息变得越来越困难。 在过去的十年中，随着单分子晶体管（SMT）的发展，这种缩放的极限已经达到，其中电流的关键通道是1-2 nm大小的小分子。 这些器件是研究纳米级传导物理学的绝佳工具，包括耗散的起源和电子-电子相互作用的重要性。 该奖项支持一个项目，其目标是将SMT研究扩展到电传导之外，以包括电噪声的测量。 噪声，在通过设备的电流波动的形式，预计提供有价值的信息，振动和磁过程内的SMT。 两名研究生将接受最先进的纳米制造方法的培训，并将使用低频和高频技术来测量各种条件下SMT中的噪声，从而为未来的学术或工业生涯做好准备。 如果成功，研究结果将为未来技术相关的物理学提供新的见解，而工作本身将为进一步的新测量打开大门，包括检测和操纵单电子自旋。* 技术摘要 * 单分子晶体管（SMT）是在过去十年中发展起来的，是研究纳米尺度传导物理的杰出工具。 SMT是高度量子力学系统，其中电子-电子，电子-振动和基于自旋的相互作用都可以很强。 理解这种结构的一个持续挑战是通过电子传导的DC表征获得的信息有限。 更高频率的传导测量以及散粒噪声可以提供更深入的了解电子振动和强相关效应的作用。 散粒噪声特别提供了有关电子隧道事件之间相关性的信息。 该奖项支持使用低频和高频方法测量各种条件下SMT散粒噪声的项目。 在含有未成对电子的SMT中，散粒噪声将用于测试理论预测，即当通过近藤过程进行传输时，电子的有效电荷被修改为分数值。 这些测量将奠定基础，为最终发展的高频率？RF-SMT？和可能的单分子电子自旋共振。 该计划将为两名研究生提供纳米科学制造和测量技术的最先进培训，从而为他们未来的学术或工业研究职业做好准备。

****NON-TECHNICAL ABSTRACT****The transistor is the underpinning of the Information Age. Over the last sixty years, the transistor has been reduced from several centimeters to a few tens of nanometers, with each device now more than 1000 times smaller than the diameter of a human hair. As sizes are reduced further, quantum effects become critically important in determining device properties. At the same time, it becomes increasingly difficult to acquire information about the detailed geometry and material quality of the devices. In the last decade the ultimate limit of this scaling has been reached with the development of single-molecule transistors (SMTs), where the critical channel for current is a small molecule 1-2 nm in size. These devices are excellent tools for examining the physics of conduction at the nanoscale, including the origins of dissipation and the importance of electron-electron interactions. This award supports a project with the goal of extending SMT studies beyond electrical conduction to include measurements of electrical noise. Noise, in the form of fluctuations in the current through the device, is predicted to provide valuable information about both vibrational and magnetic processes within SMTs. Two graduate students will be trained in state-of-the-art nanofabrication methods and will use both low- and high-frequency techniques to measure the noise in SMTs under various conditions, thus preparing them for future academic or industrial careers. If successful the research results will provide new insights into the physics relevant to future technologies, while the work itself will open the door to further new measurements, including the detection and manipulation of single electron spins. ****TECHNICAL ABSTRACT****Single-molecule transistors (SMTs) have been developed over the last decade, and have been outstanding tools for examining the physics of conduction at the nanometer scale. SMTs are highly quantum mechanical systems where electron-electron, electron-vibrational, and spin-based interactions can all be strong. One persistent challenge in understanding such structures is the limited information available through DC characterization of electronic conduction. Higher frequency measurements of conduction as well as shot noise can provide much deeper insight into the roles of electron-vibrational and strong correlation effects. Shot noise in particular gives information about the correlations between electron tunneling events. This award supports a project to use both low- and high-frequency methods to measure shot noise in SMTs under various conditions. In SMTs containing unpaired electrons, shot noise will be used to test the theoretical prediction that the effective charge of the electron is modified to a fractional value when transport takes place via the Kondo process. These measurements will lay the groundwork for the eventual development of high frequency ?RF-SMTs? and possible single-molecule electron spin resonance. This program will provide state-of-the-art training of two graduate students in nanoscale science fabrication and measurement techniques thereby preparing them for future careers in academic or industrial research.