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

分光计测量光的光谱组成。中红外光谱仪工作在2-9微米的光谱范围内，可用于许多重要应用，如气体传感、热成像、微生物检测和监测。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。虽然在光谱仪的小型化方面已经取得了重大进展，但目前大多数紧凑型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分量，导致占用的空间远远大于工作波长。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段，而开发集成片上中红外光谱仪的努力非常有限，尽管它们具有重要的技术意义。在这个项目中，将利用范德华异质结构和先进的数学算法，开发基于单个芯片上可调传感器的中红外光谱仪。拟议的研究包括对新兴材料的光学性质的研究、器件制造和数值分析。科学地讲，这项研究将揭示新兴范德华异质结构中的光-物质相互作用特性。这一结果将导致超小型、片上光谱仪在关键但较少探索的中红外波长范围内。在这个项目中，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，从而为发展半导体行业的下一代劳动力做出贡献。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在科学、技术、工程和数学领域追求职业生涯。该项目的目标是开发一种高度紧凑的中红外光谱仪，该光谱仪基于单一的、可调谐的范德华异质结构光电探测器。首先，该团队将从理论和实验上研究中红外波段范德华异质结构中的可调谐光-物质相互作用，为拟议的计划奠定基础。其次，我们将展示可调谐的范德华异质结构光电探测器，并将在不同的偏置条件下表征其可广泛调谐的光响应矩阵。最后，该团队将开发算法和测量方案，以演示基于已知的可调光响应特性的光谱功能。拟议的计划旨在开发中红外光谱分析的新范例。以前的片上光谱仪通常使用多个光检测元件来检测光的不同光谱分量，并且光谱是根据这些不同元件的测量来重建的。一旦制造出来，这些光电探测元件就不能再进行修改，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的基础上，并进一步利用新兴的范德华异质结构的良好物理性质来推进芯片上红外光谱的前沿。建议的光谱仪克服了传统芯片上光谱仪的分辨率限制，使光谱功能能够在与操作波长相当的占地面积内实现。该项目是高度跨学科的，利用材料科学、凝聚态物理和电气工程的最新发展来提供备受期待的、具有变革性的范德华材料应用。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。

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.