Collaborative Research: Composite Avalanche Nanoantenna Room-Temperature Infrared Photodetectors (CANTRIP)

在2019冠状病毒病大流行期间，我们许多人都熟悉了红外成像，作为一种快速筛查发烧患者的方法。然而，红外成像在其他医疗诊断、天文学、执法、军事视觉系统、机械/电气部件检查、安全通信、能源/环境评估以及更多情况下也很有用。尽管这些广泛的应用，红外成像仪是昂贵的，通常需要内部冷却系统。这项工作将开发出一种新型的热成像仪，它具有更便宜、更节能的潜力，并且具有目前使用现有技术无法实现的额外功能。这一领域的突破将使热成像成为日常生活的一部分。在这项工作中，研究人员将创建将纳米级天线与光电探测器集成在一起的混合探测器，与目前的先进系统相比，这应该能够增加功能，同时降低系统成本和复杂性。两位研究人员都有将他们的研究与更广泛的社区相结合的悠久历史；通过这项工作，他们计划发起关于光、材料和结构相互作用的新拓展努力，向不同年龄和背景的学生展示“观看无形”的兴奋。本研究旨在利用纳米天线阵列和雪崩二极管技术的结合，开发一种用于室温、长波红外（LWIR）光探测的全新机制。我们将结合：a)有源光子设计，b)天线阵列理论和c)定制半导体材料/器件来推进光探测的状态。随着后期的发展（例如实现高填充系数的微透镜阵列），这些光电探测器可能成为取代现有昂贵成像仪的新主导范例。我们的解决方案结合了光探测技术和各向异性纳米天线设计，创造了一流的混合光探测系统。这种新颖的组合依赖于有源频率选择系统和高灵敏度雪崩光电二极管的理论基础。为了实现这一基础，必须研究与混合半导体/金属纳米天线建模相关的挑战，因为除了少数例外，集成光学响应与半导体载流子迁移率的需求在很大程度上被忽视了。虽然，许多相关的相互作用已经成功地独立建模，但在产生集成电磁激励与半导体载流子迁移率和电荷分布的全波模拟方面存在重大障碍。我们的模型将结合局部载流子注入和输运建模，以开发雪崩二极管的生长曲线，包括半导体选择、带隙、掺杂曲线和层厚度。这些参数的相互作用与传统的光电二极管材料系统有着根本的不同，将通过分析来从根本上理解纳米结构/半导体的相互作用。由于材料系统的选择是该项目成功的一个重要因素，该项目将考虑基于GaAs的雪崩二极管，以及InP和/或GaP，因为III-V异质结材料系统的多功能性使其能够适应新的挑战。在这项工作中使用的分子束外延系统能够混合任何常见的III-V元素（Al, Ga, in， Tl和P， As, Sb, Bi），以实现广泛的潜在材料性能。因此，可以使用半导体生长曲线和掺杂浓度来调整局部载流子注入等参数，以实现所需的诱导光电流。通过对建模、各向异性天线设计和独特的半导体生长曲线的深入分析，这项工作为理解革命性的电磁成像架构提供了一条新的途径。具体来说，我们正在使用红外信号来激发各向异性纳米天线，这将激发集成半导体结中的雪崩过程。由此产生的室温光电探测器将最大限度地减少热噪声，增加功能，并成为一流的创新。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Many of us have become familiar with infrared (IR) imaging during the COVID-19 pandemic as a method to rapidly screen for people with fevers. However, IR imaging is also useful for other medical diagnosis, astronomy, law enforcement, military vision systems, inspection of mechanical/electrical components, secure communications, energy/environmental assessments, and many more situations. Despite these broad applications, IR imagers are expensive and generally require internal cooling systems. This work would develop a new class of thermal imager with the potential to be cheaper, more energy efficient, and operable with additional functionalities not presently available using existing technology. A breakthrough in this area will enable thermal imaging to become part of everyday life. In this work, the investigators will create hybrid detectors that integrate nanoscale antennas with photodetectors, which should enable increased functionality while also reducing system cost and complexity compared to the present state of the art systems. Both investigators have a long history of outreach of integrating their research with the broader community; and through this work, they plan to initiate new outreach efforts about the interaction of light, materials, and structures to show students of a variety of ages and backgrounds the excitement of “viewing the invisible.”This research aims to develop a fundamentally new mechanism for room temperature, long wavelength infrared (LWIR) photodetection using a combination of nanoantenna arrays and avalanche diode technologies. We will advance the state of photodetection by combining: a) active photonic design, b) antenna array theory, and c) customized semiconductor materials/devices. With later development (e.g. microlens arrays for achieve high fill factors) these photodetectors could become the new dominant paradigm replacing the existing, costly imagers. Our solution combines photodetection technologies and anisotropic nanoantenna designs to create a first-in-class, hybrid photodetection system. This novel combination relies on the theoretical foundation of active frequency selective systems and those of highly sensitive avalanche photodiodes. To achieve this foundation, the challenges associated with a hybrid semiconductor/metallic nanoantenna modeling must be investigated as, with only a few exceptions, the need to integrate optical responses with semiconductor carrier mobility has been a largely overlooked area. Although, many of the associated interactions have been successfully modeled independently, there have been significant hurdles in producing full-wave simulation which integrate electromagnetic excitations with semiconductor carrier mobilities and charge distributions. Our models will incorporate localized carrier injection and transport modeling to develop an avalanche diode growth profile including semiconductor choice, bandgap, doping profile, and layer thickness. The interplay of these parameters is fundamentally different than traditional photodiode material systems will be analyzed to understand the nanostructure/semiconductor interactions at a fundamental. Since the choice of material system is an important one for this project to succeed, the project will consider GaAs based avalanche diodes, as well as InP and/or GaP due to the versatility of the III-V heterojunction materials system enabling adaptability as new challenges arise. The molecular beam epitaxy systems employed in this work are capable of intermixing any of the common III-V elements (Al, Ga, In, Tl and P, As, Sb, Bi) to achieve a wide range of potential material properties. As such, parameters such as the localized carrier injection can be adjusted using semiconductor growth profiles and doping concentrations to achieve the desired induced photocurrent. Through the thorough analysis of modeling, anisotropic antenna design, and unique semiconductor growth profiles, this work provides a novel path to understanding a revolutionary electromagnetic imaging architecture. Specifically, we are using an IR signal to excite an anisotropic nanoantenna which will stimulate the avalanche process in an integrated semiconductor junction. The resulting room-temperature photodetectors will minimize thermal noise, increase functionality, and be a first-in-class-innovation.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.