Influence of Geometry on Quasi-Ballistic Behavior in Silicon Nanowire Geometric Diodes
Influence of Geometry on Quasi-Ballistic Behavior in Silicon Nanowire Geometric Diodes
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DOI：
10.1021/acsanm.2c04666
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发表时间：
2023-03
影响因子：
5.9
通讯作者：
Kelly L. White;Max A. Umantsev;Jeremy D. Low;James P. Custer;J. Cahoon
中科院分区：
文献类型：
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作者：
Kelly L. White;Max A. Umantsev;Jeremy D. Low;James P. Custer;J. Cahoon
二极管是控制电荷流动的电路的基本组件，而几何二极管(GDS)是一种特殊的类型，它可以使用弹道或准弹道传输结合几何不对称来优先将载流子引导到一个方向，从而实现电子棘轮效应。纳米材料为GDS的发展提供了一个独特的平台，基于硅纳米线(NW)的GDS─柱状对称但平移不对称的三维纳米结构─最近被证明在室温下具有功能。这些器件理论上可以实现接近零偏置的开启电压，并可整流至太赫兹频率。在这里，我们合成了硅NW GDS，并制造了单NW器件，从这些器件中可以观察到二极管性能的显著变化，而几何结构的变化相对较小。为了阐明几何和弹道行为之间的相互作用，我们发展了一个蒙特卡罗模拟来描述三维NW GD中电子的准弹道行为。我们研究了掺杂水平、温度和几何形状对载流子输运的影响，揭示了电荷载流子平均自由程(MFP)、表面镜面反射和几何形状对GD性能的影响。正如预期的那样，几何形状通过引导或阻止电荷载流子通过纳米结构强烈地影响性能。有趣的是，我们发现阻挡效应至少和导向效应一样重要。此外，在某些几何限制内，二极管行为对MFP的敏感度比最初可能预期的要低，因为相关的长度标度较短，并且阻塞效应很重要。研究结果为NW GDS的未来设计提供了指导，并使实验结果的趋势预测和解释成为可能。提高对准弹道传输的理解对于指导未来的实验实现太赫兹整流在高速数据传输和长波能量采集中的应用至关重要。
Diodes are a basic component of electrical circuits to control the flow of charge, and geometric diodes (GDs) are a special class that can operate using ballistic or quasi-ballistic transport in conjunction with geometric asymmetry to direct charge carriers preferentially in one direction, enabling an electron ratcheting effect. Nanomaterials present a unique platform for the development of GDs, and silicon nanowire (NW)-based GDs─cylindrically symmetric but translationally asymmetric three-dimensional nanostructures─have recently been demonstrated functioning at room temperature. These devices can theoretically achieve a near zero-bias turn-on voltage and rectify up to THz frequencies. Here, we synthesize silicon NW GDs and fabricate single-NW devices from which significant changes in diode performance are observed from relatively minor changes in geometry. To elucidate the interplay between geometry and ballistic behavior, we develop a Monte Carlo simulation that describes the quasi-ballistic behavior of electrons within a three-dimensional NW GD. We examine the effects of doping level, temperature, and geometry on charge carrier transport, revealing the relationships between charge carrier mean free path (MFP), specular reflection at surfaces, and geometry on GD performance. As expected, geometry strongly influences performance by directing or blocking charge carrier passage through the nanostructure. Interestingly, we find that the blocking effect is at least as important as the directing effect. Moreover, within certain geometric limits, the diode behavior is less sensitive to the MFP than might be initially expected because of the short relevant length scales and importance of the blocking effect. The results provide guidelines for the future design of NW GDs and enable the prediction and interpretation of trends in experimental results. An improved understanding of quasi-ballistic transport is crucial to guiding future experiments toward realizing THz rectification for applications in high-speed data transfer and long-wavelength energy harvesting.