FuSe: Electronic-photonic heterogeneous integration for sensing above 1 THz

该项目的目标是提高传统硅基半导体电子设备和系统的高频操作极限，使它们能够产生和检测频率高于1太赫兹（THz）的电磁辐射。在硅晶圆厂使用标准工艺制造的双极CMOS （BiCMOS）芯片已被证明产生接近甚至超过1太赫兹的辐射。然而，一般来说，这种电子设备（如半导体晶体管、二极管）很难在如此高的频率下产生显著水平的功率，部分原因是驱动天线的振荡电子不能足够快地来回移动。然而，1太赫兹是电子和光子器件（如激光）之间的自然交叉点。光子器件不受自由电子移动速度的限制，因为它们产生的辐射基于不同的原理：由于电子在量子化能级之间的跃迁，太赫兹光子的受激发射。这种现象将被用来制造量子级联（QC）光子放大器（由III-V半导体制成），它将放大硅BiCMOS电子芯片产生的微弱太赫兹信号。为此，将采用新颖的微加工技术将BiCMOS电子芯片与III-V激光芯片紧密集成在一个共同的硅互连结构上。该项目最终将展示一个系统，该系统使用这些太赫兹信号来检测各种气体的“光谱指纹”，包括几种大气环境毒素。本研究解决了半导体技术面临的一个重大挑战：如何将集成电路半导体技术扩展到完全覆盖太赫兹范围。该应用具有重大的社会影响，例如环境传感（例如住宅空气质量，污染物监测），以及工业/国防/航空气体传感（例如用于能源，推进和行星进入）和科学（天体物理学，火灾科学，燃烧）。劳动力发展将围绕一个强大的本科生研究项目来组织，这是一个吸引和留住学生的成熟策略。将招募一批带薪的本科生研究人员，特别关注即将入学的转学生、未被充分代表的少数民族学生和系里的荣誉学生。除了参与研究之外，他们还将参加一个强大的专业发展计划，一个基于半导体的学术课程（包括微加工），并参加行业实习。该项目的目标是通过(a)开发一种硅BiCMOS芯片的异质集成系统，该系统使用III-V太赫兹量子级联（QC）激光增益材料产生太赫兹脉冲，(b)使用该系统开发一种混合太赫兹双梳发射器/接收器，用于1.5太赫兹以上的多外差光谱。(c)演示该系统在环境和工业监测中的多气体传感应用。该方法建立在特别设计的BiCMOS频率梳发生器芯片上，该芯片已被证明可以发射高达3太赫兹的信号（尽管输出功率较低）；这些信号将被太赫兹QC行波功率放大器放大。其智力优势首先在于利用量子级联光子增益材料，将bicmos代工电子器件的性能扩展到1thz以上。由此产生的混合系统将展示CMOS的优势（尺寸和重量更小，集成度和信号处理能力更高），并产生超过1太赫兹的III-V量子级联激光器。其次，优点在于开发了太赫兹硅互连结构，它将利用先进的芯片技术将BiCMOS和III-V芯片放置在具有微米级校准精度的近距离上，用于低损耗太赫兹互连。本研究涉及三个层面：材料（QC材料开发）、器件（异质集成结构、BiCMOS太赫兹集成电路和QC放大器）和系统（用于气体传感的双梳状光谱）。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。

The goal of this project is to boost the high-frequency operating limit for conventional silicon-based semiconductor electronic devices and systems so that they can generate and detect electromagnetic radiation with frequencies above 1 terahertz (THz). Bipolar CMOS (BiCMOS) chips fabricated at silicon foundries using standard processes have been shown to generate radiation approaching, and even exceeding 1 THz. However, in general such electronic devices (e.g. semiconductor transistors, diodes) have difficulty to generate significant levels of power at such high frequencies, in part because the oscillating electrons which drive the antennas cannot travel back and forth quickly enough. However, 1 THz is a natural crossover point between electronic and photonic devices (e.g. lasers). Photonic devices are not limited by how fast free electrons move, because they generate radiation based upon a different principle: the stimulated emission of terahertz photons due to transitions of electronic between quantized energy levels. This phenomenon will be leveraged to create quantum-cascade (QC) photonic amplifiers (made of III-V semiconductors) that will amplify the weak terahertz signals generated by silicon BiCMOS electronic chips. Towards this end, novel microfabrication techniques will be used to integrate the BiCMOS electronic chips with the III-V laser chips in close proximity on a common silicon interconnect fabric. This project will culminate in the demonstration of a system that uses these terahertz signals to detect the “spectral fingerprints” of various gasses – including several which are atmospheric environmental toxins. This research addresses a grand challenge for semiconductor technology: how to extend integrated circuit semiconductor technology to fully cover the terahertz range. This application has significant societal impact, such as in environmental sensing (e.g. residential air quality, pollutant monitoring), as well as industrial/defense/aero gas sensing (e.g. for energy, propulsion, and planetary entry), and science (astrophysics, fire science, combustion). Workforce development will be organized around a robust undergraduate research program – a well-established strategy for attracting and retaining students to a discipline. A cohort of paid undergraduate researchers will be recruited, particularly focusing on incoming transfer students, underrepresented minority students, and departmental honors students. In addition to participation in research, they will participate in a robust professional development program, a semiconductor based academic curriculum (including microfabrication), and participation in industry internships.The goal of this project is to extend the reach of high-frequency semiconductor electronics above 1 THz by (a) developing a system for heterogeneous integration of silicon BiCMOS chips that generate THz pulses with III-V terahertz quantum-cascade (QC) laser gain material, (b) using this system to develop a hybrid THz dual-comb transmitter/receiver for multi-heterodyne spectroscopy above 1.5 THz, and (c) demonstrating this system for multi-gas sensing with applications in environmental and industrial monitoring. The approach builds upon specially designed BiCMOS frequency-comb generator chips that have been shown to emit signals up to 3 THz (albeit with low output power); these signals will then be amplified by THz QC travelling-wave power amplifiers. The intellectual merit lies first in the use of quantum-cascade photonic gain material to extend the performance of BiCMOS-foundry electronics above 1 THz. The resulting hybrid systems will exhibit the advantages of CMOS (reduced size and weight, increased integration and signal processing capability), with the power generation of III-V quantum-cascade lasers above 1 THz. Second, merit lies in the development of a terahertz silicon interconnect fabric, which will leverage advanced chiplet technology to place BiCMOS and III-V chiplets in close proximity with micron-scale alignment precision for low-loss THz interconnects. This research addresses three levels on the stack: materials (QC material development), devices (heterogeneous integration fabric, BiCMOS THz integrated circuits, and QC-amplifiers), and systems (dual-comb spectroscopy for gas sensing).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.