Composite Avalanche Nanoantenna Room-Temperature Infrared Photodetectors (CANTRIP)

在新冠肺炎大流行期间，我们许多人都熟悉红外成像，将其作为一种快速筛查发烧患者的方法。然而，红外成像也可用于其他医疗诊断、天文学、执法、军事视觉系统、机械/电气部件检测、安全通信、能源/环境评估以及更多情况。尽管有这些广泛的应用，但红外成像仪价格昂贵，通常需要内部冷却系统。这项工作将开发一种新的热成像仪，具有更便宜、更节能、可操作的潜力，并具有目前使用现有技术无法提供的额外功能。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，研究人员将创造将纳米级天线与光电探测器相结合的混合探测器，与目前最先进的系统相比，这应该会增加功能，同时还会降低系统成本和复杂性。这两位研究人员在将他们的研究与更广泛的社区相结合方面有着悠久的历史；他们计划通过这项工作，启动关于光、材料和结构相互作用的新推广工作，向不同年龄和背景的学生展示“看不见的东西”的兴奋。这项研究旨在利用纳米天线阵列和雪崩二极管技术的组合，开发一种全新的室温、长波红外线(LWIR)光探测机制。我们将结合：a)主动光子设计，b)天线阵列理论，c)定制半导体材料/器件，来推进光探测的状态。随着以后的发展(例如，用于实现高填充系数的微透镜阵列)，这些光电探测器可能成为新的主导范例，取代现有的昂贵的成像器。我们的解决方案结合了光检测技术和各向异性纳米天线设计，创建了一流的混合光检测系统。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，必须研究与半导体/金属纳米天线混合建模相关的挑战，因为除了少数例外，将光学响应与半导体载流子迁移率相结合的需要在很大程度上被忽视了。尽管许多相关的相互作用已经被成功地独立建模，但在产生将电磁激发与半导体载流子迁移率和电荷分布相结合的全波模拟方面存在重大障碍。我们的模型将结合局域载流子注入和输运模型来开发雪崩二极管生长轮廓，包括半导体选择、带隙、掺杂轮廓和层厚度。这些参数的相互作用从根本上不同于传统的光电二极管材料系统的分析，以从根本上了解纳米结构/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，以及由于III-V异质结材料系统的多功能性，能够适应出现的新挑战的InP和/或GaP。本工作所采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)，以获得广泛的潜在材料性质。因此，可以使用半导体生长曲线和掺杂浓度来调整诸如局域载流子注入之类的参数，以获得所需的感生光电流。通过对建模、各向异性天线设计和独特的半导体生长轮廓的深入分析，这项工作为理解革命性的电磁成像体系结构提供了一条新的途径。具体地说，我们正在使用红外信号来激励各向异性纳米天线，这将刺激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NSF的法定使命，并通过使用基金会的智力优势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.