Collaborative Research: NSF-BSF: On-Chip High-Resolution Mid-Infrared Spectroscopy with a Single Tunable van der Waals Heterostructure Photodetector

光谱仪测量光的光谱组成。中红外光谱仪，在2-9µm光谱范围内工作，可用于许多重要的应用，如气体传感，热成像，微生物检测和监视。传统的光谱仪体积庞大，价格昂贵，通常由机械运动部件组成。尽管在光谱仪的小型化方面已经取得了重大进展，但目前，大多数紧凑的光谱仪仍然由一系列芯片上的组件组成，以捕获光的不同光谱成分，导致占地面积远远大于工作波长。此外，目前开发紧凑型光谱仪的研究主要集中在可见光和近红外波长范围内，而开发集成片上中红外光谱仪的努力非常有限，尽管其技术意义重大。在该项目中，将开发基于单个片上可调谐传感器的中红外光谱仪，利用范德华异质结构和先进的数学算法。提出的研究包括调查新兴材料的光学性质，器件制造和数值分析。科学上，本研究将揭示新兴范德华异质结构中光-物质相互作用的性质。该结果将导致在关键但较少探索的中红外波长范围内的超紧凑片上光谱仪。通过该项目，博士后研究人员以及研究生和本科生将获得半导体器件设计和制造方面的知识，从而为半导体行业的下一代劳动力发展做出贡献。这些外展活动将提高公众对科学的理解，并鼓励代表性不足的群体从事科学、技术、工程和数学方面的职业。这个项目的目标是开发一个高度紧凑的中红外光谱仪，基于一个单一的，可调谐的范德华异质结构光电探测器。首先，该团队将从理论上和实验上研究中红外波长范围内范德瓦尔斯异质结构中可调谐的光-物质相互作用，为提出的计划奠定基础。其次，将展示可调谐范德华异质结构光电探测器，并将在不同偏置条件下表征其广泛可调谐的光响应矩阵。最后，该团队将开发算法和测量方案，以展示基于已知可调谐光响应特性的光谱功能。该计划旨在开发中红外光谱的新范例。以前的片上光谱仪通常使用多个光探测元件来检测光的不同光谱成分，光谱是根据这些不同元素的测量结果重建的。一旦制成，这些光探测元件就不能再修改，从而限制了这些光谱仪的分辨率和工作波长范围。提出的异质结构光谱仪将建立在一种新的可调谐单元素光电探测器方案上，并进一步利用新兴范德华异质结构的有前途的物理性质来推进片上红外光谱的前沿。提出的光谱仪克服了传统片上光谱仪的分辨率限制，并使光谱功能在与操作波长相当的足迹内实现。该项目是高度跨学科的，并利用材料科学，凝聚态物理和电气工程的最新发展，提供备受期待的范德华材料的变革性应用。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。

Spectrometers measure the spectral composition of light. Mid-infrared spectrometers, operational in 2-9 µm spectral range, can be used in many important applications such as gas sensing, thermal imaging, microbial detection, and surveillance. Traditional spectrometers are bulky, expensive, and usually consist of mechanically moving parts. Although significant progress has been made in the miniaturization of spectrometers, currently, most compact spectrometers still consist of an array of on-chip components to capture the different spectral components of the light, leading to a footprint much larger than the operational wavelength. Moreover, current research on developing compact spectrometers focuses on visible and near-infrared wavelength range, and the effort on developing integrated on-chip mid-infrared spectrometers is very limited despite their technical significance. In this project, mid-infrared spectrometers based on a single, on-chip, tunable sensor will be developed, leveraging van der Waals heterostructures and advanced mathematical algorithms. The proposed research involves investigations of the optical properties of emerging materials, device fabrication, and numerical analysis. Scientifically, this research will reveal the light-matter interaction properties in emerging van der Waals heterostructures. The results will lead to ultracompact, on-chip spectrometers in the critical, but less-explored, mid-infrared wavelength range. In this project, postdoctoral researchers, and graduate and undergraduate students will acquire knowledge in semiconductor device design and fabrication, thus contributing to the development of next-generation workforce for semiconductor industry. The outreach activities will improve the scientific understanding of the general public and encourage underrepresented groups to pursue careers in science, technology, engineering, and math. The goal of this project is to develop a highly compact, mid-infrared spectrometer based on a single, tunable van der Waals heterostructure photodetector. First, the team will investigate the tunable light-matter interactions in van der Waals heterostructures in the mid-infrared wavelength range both theoretically and experimentally, laying the foundation for the proposed program. Second, tunable van der Waals heterostructure photodetectors will be demonstrated and their widely tunable photoresponse matrices will be characterized under different biasing conditions. Finally, the team will develop algorithms and measurement schemes to demonstrate spectroscopy functions based on the known tunable photoresponse characteristics. The proposed program aims to develop new paradigms for mid-infrared spectroscopy. Previous on-chip spectrometers usually utilize multiple photodetection elements to detect different spectral components of the light, and the spectrum is reconstructed from measurements from these various elements. Once fabricated, these photodetection elements can no longer be modified, thus limiting the resolution and the operational wavelength range of these spectrometers. The proposed heterostructure spectrometer will build upon a novel tunable single-element photodetector scheme, and further leverage the promising physical properties of emerging van der Waals heterostructures to advance the frontiers of on-chip infrared spectroscopy. The proposed spectrometer overcomes the resolution limitations of traditional on-chip spectrometers and enables spectroscopic functionality within a footprint comparable to the wavelength of the operation. The project is highly interdisciplinary and leverages latest developments in material sciences, condensed matter physics, and electrical engineering to deliver much-anticipated, transformative applications with van der Waals materials.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.