Ratcheting Electrons with Silicon Geometric Diodes for Quasi-ballistic Terahertz Rectennas

二极管是电路的基本元件，用于控制电流的流动。它们对几乎所有电子设备的操作都至关重要，从笔记本电脑到相机。虽然二极管已经存在了几十年，但它们通常在制造容易程度和操作速度方面存在局限性。在这个项目中，一个相对较新类型的二极管称为几何二极管将制造和测试。二极管制造相对简单，并且可以潜在地以非常高的速度工作。为了制造二极管，由硅组成的微观导线将被生长成漏斗状。然后，这些结构将被测试其在一个方向上而不是相反方向上汇集电流的能力，这种效果类似于棘轮。二极管将在更高的速度下进行逐步测试，以确定其最终性能极限。从该项目的成果中获得的技术在成像、数据传输、通信、安全检查和能量收集方面具有潜在的应用。该项目还将培训学生在多个年级，其结果将通过出版物，会议和公共宣传活动进行传播。技术摘要：弹道整流器是一种特殊的二极管，通常在二维电子气系统中通过设计非对称结构与高分辨率光刻来制造。两端硅纳米线几何二极管是一种替代和非传统的策略，以生产能够高频整流的电子二极管。二极管是几何非对称的纳米结构，其通过准弹道机制操作，导致弹道电子被引导通过前向方向上的收缩，但被反向反射。电流流动中的这种不对称性导致电子的棘轮效应以及在施加交流（AC）信号时产生直流（DC）偏置。最重要的是，弹道操作机制表明，这些结构可以潜在地将AC信号整流到太赫兹（THz）区域。通过实验和建模相结合，本项目将开发和演示纳米线几何二极管的性能管理的设计原则。这些二极管将通过制造单纳米线整流天线并用太赫兹辐射照射来测试太赫兹范围。总的来说，这些研究将揭示纳米线几何二极管的基本特性，并突出其作为一类新的高频整流器的潜力。这项工作涉及到从高中到研究生的多个层次的学生，他们的项目在材料科学、物理学和电气工程之间架起了一座桥梁，为参与的学生提供了广泛的经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Abstract:Diodes are a basic component of electric circuits and are used to control the flow of current. They are vital to the operation of nearly all electronic devices, from laptop computers to cameras. Although diodes have existed for many decades, they typically have limitations in terms of how easy they are to make and how quickly they can operate. In this project, a relatively new type of diode termed a geometric diode will be fabricated and tested. The diodes are relatively simple to fabricate and can potentially operate at very high speeds. To create the diodes, microscopic wires composed of silicon will be grown to have a funnel-like shape. These structures will then be tested for their capacity to funnel current in one direction but not in the opposite, an effect that is similar to a ratchet. The diodes will be progressively tested at higher speeds to determine their ultimate performance limits. Technology derived from the outcomes of this project has potential applications in imaging, data transfer, communications, security screening, and energy harvesting. The project will also train students at multiple grade levels, and the results will be disseminated through publications, conferences, and public outreach events.Technical Abstract:Ballistic rectifiers represent a special class of diode typically fabricated in two-dimensional electron gas systems by designing an asymmetric structure with high-resolution lithography. Two terminal silicon nanowire geometric diodes are an alternate and unconventional strategy to produce electrical diodes capable of high-frequency rectification. The diodes are geometrically-asymmetric nanostructures that operate via a quasi-ballistic mechanism, causing ballistic electrons to be directed through a constriction in the forward direction but to be reflected backwards in the reverse. This asymmetry in the flow of current causes the ratcheting of electrons and generation of a direct current (DC) bias upon application of an alternating current (AC) signal. Most importantly, the ballistic mechanism of operation indicates that these structures can potentially rectify AC signals into the terahertz (THz) regime. Through a combination of experiment and modeling, this project will develop and demonstrate the design principles that govern the performance of nanowire geometric diodes. The diodes will be tested in the THz regime by fabricating single-nanowire rectennas and illuminating with THz radiation. Overall, the studies will reveal fundamental characteristics of nanowire geometric diodes and highlight their potential to serve as a new class of high-frequency rectifier. The effort involves students at multiple levels—from high-school through graduate—with a project that bridges the interface between materials science, physics, and electrical engineering, providing breadth of experience for the students involved.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.