Collaborative Research: A Roadmap Toward Terahertz Optoelectronics Using Active Control of Charge Density Waves at Degenerate Semiconductor Interfaces

过去几十年的信息革命是由微处理器技术的前所未有的进步和向更小、更快和更有效的电子设备的不断发展所推动的。因此，在电信、计算、金融、国家安全和太空探索等人类活动的不同领域，都实现了令人瞩目的新能力。尽管取得了这些进展，但在过去几年中，与电子互连延迟时间和散热相关的缩放问题导致微处理器时钟速度在约3GHz处饱和。光子集成电路是电子电路的模拟，但以光子取代电子作为信息载体，具有极高的数据承载能力，并有可能解决微处理器技术目前的一些瓶颈。然而，目前用于光子电路中的介质波导和互连在尺寸上受到衍射基本定律的限制，导致电子和光子组件之间的尺寸失配。因此，除了电信之外，它们在现实世界设备中的实际实现受到了很大的阻碍。在这里，我们提出了一种新的数据处理元件，光电开关，它吸收了光子学和电子学的最佳特性。它有可能解决电子设备当前的信息带宽限制，同时使设备尺寸大大小于传统的光子元件。这项工作的一个重大影响将是为研究生和本科生（包括代表性不足的群体）培养尖端研究机会，实施新的教学方法，并通过让高中学生参与数学和科学方面的有趣主题来追求更广泛的推广。这项提案旨在开发一种新的光电设备，称为表面等离子体二极管，其操作基于对在重掺杂（简并）半导体界面处传播的电荷密度波的主动控制。理论和实验之间的协同作用将被追求，以深入了解复杂的多物理现象背后的设备操作，包括电荷传输和重组在高梯度，重掺杂pn+结，空间和时间相关的局部介电常数的变化在半导体界面，由于欧姆加热和电磁能量耗散的热效应。实验工作将导致基于绝缘体上硅和外延生长III-V族半导体材料和化合物的概念验证器件。体材料生长/制造和表征将为理论建模提供信息，这反过来又将指导原型的制造和实验表征。将使用直接检测方法（IR检测器）测试器械的瞬态响应，调制速率范围为低（kHz）至中高频（几MHz至3GHz）。对于高于3GHz的数据速率，将实施新的片上电光检测。这些实验测量，结合理论，将建立物理限制和缩放定律，控制设备的3dB带宽，并建立一个清晰的路线图，直接，电光信号调制速率下降到皮秒时间尺度的信号调制超过-10dB和模式大小，大大小于目前的光电子元件。拟议的研究提出了一种新的方法，以快速光学互连，电路和逻辑元件，并可能导致突破性的技术相关的集成光学和电子，一个数十亿美元的产业。

The information revolution of the past decades has been driven by unprecedented advances in microprocessor technology and a continuous progression towards smaller, faster and more efficient electronic devices. As a result, remarkable new capabilities have been enabled across vastly different areas of human activity such as telecommunication, computation, finances, national security and space exploration. Despite this progress, the past few years has seen scaling issues associated with electronic interconnect delay times and heat dissipation result in the saturation of microprocessor clock speeds at about 3GHz. Photonic integrated circuits, being the analogue of electronic circuits but with photons substituting for electrons as the information carrier, possess an exceedingly high data-carrying capacity and have the potential to address some of the present bottlenecks in microprocessor technology. However, the dielectric waveguides and interconnects currently used in photonic circuits are limited in size by the fundamental law of diffraction, leading to dimensional mismatch between electronic and photonic components. As a result, their practical implementation in real-world devices, apart from telecommunications, has been substantially hindered. Here we propose a new data processing element, an optoelectronic switch, which assimilates the best characteristics of photonics and electronics. It has the potential to address the current information bandwidth limitations of electronic devices, while simultaneously enabling device sizes that are substantially smaller than traditional photonic elements. A significant impact of this work will be the fostering of cutting-edge research opportunities for graduate and undergraduate students, including from underrepresented groups, implementing a new teaching methodology and pursuing a broader outreach by engaging high school children with fascinating topics in math and sciences.This proposal seeks to develop a new optoelectronic device, referred to as Surface Plasmon Diode, with operation based on active control of charge-density waves propagating at heavily doped (degenerate) semiconductor interfaces. A synergy between theory and experiment will be pursued to gain insight into the complex multi-physics phenomena behind the device operation, including charge transport and recombination at high-gradient, heavily doped pn+- junctions, spatially and time dependent local permittivity variations at the semiconductor interfaces, and thermal effects due to Ohmic heating and electromagnetic energy dissipation. The experimental efforts will lead to Proof of Concept devices based on Silicon-on-Insulator and epitaxially-grown III-V semiconductor materials and compounds. Bulk material growth/fabrication and characterization will inform the theoretical modeling, which in turn will guide the fabrication and experimental characterization of the prototype. The transient response of the devices will be tested using a direct detection method (IR-detector) for modulation rates ranging from low (kHz) to moderate and high frequencies (few MHz up to 3GHz). For data rates higher than 3GHz a new on-chip electro-optical detection will be implemented. These experimental measurements, in conjunction with the theory, will establish the physical limitations and scaling laws governing the device 3dB bandwidth, and establish a clear roadmap toward direct, electro-optical signal modulation at rates down to the picosecond time scale for signal modulation surpassing -10dB and mode sizes that are substantially smaller compared to present-day optoelectronics elements. The proposed research presents a new approach toward fast optical interconnects, circuitry and logic elements and may lead to breakthrough technologies related to integrated optics and electronics, a multibillion dollar industry.