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工作极限，以便它们能够产生和检测频率高于1太赫兹(THz)的电磁辐射。使用标准工艺在硅铸造厂制造的双极CMOS(BiCMOS)芯片已被证明产生接近甚至超过1THz的辐射。然而，一般来说，这种电子设备(例如半导体晶体管、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传播。然而，1太赫兹是电子器件和光子器件(例如激光器)之间的自然交叉点。光子设备不受自由电子运动速度的限制，因为它们基于不同的原理产生辐射：由于电子在量子化能级之间的跃迁而产生的太赫兹光子的受激发射。这一现象将被用来创造量子级联(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，新的微制造技术将被用来在普通的硅互连结构上紧密地集成BiCMOS电子芯片和III-V激光芯片。该项目将最终展示一种系统，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。这项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。这一应用具有重大的社会影响，例如在环境传感(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(例如能源、推进和行星进入)以及科学(天体物理、火灾科学、燃烧)方面。劳动力发展将围绕强有力的本科生研究计划进行组织-这是一项吸引和留住学生进入某一学科的成熟战略。将招募一批付费本科生研究人员，特别是针对即将到来的转学学生、代表性不足的少数民族学生和系优等生。除了参与研究，他们还将参与一个强有力的专业发展计划，一个基于半导体的学术课程(包括微制造)，以及参与工业实习。这个项目的目标是通过(A)开发一种系统，用于产生太赫兹脉冲的硅BiCMOS芯片与III-V太赫兹量子级联(QC)激光增益材料的异质集成，(B)使用该系统开发用于1.5太赫兹以上多外差光谱的混合太赫兹双梳发射器/接收器，以及(C)展示该多气体传感系统及其在环境和工业监测中的应用。这种方法建立在专门设计的BiCMOS频梳发生器芯片上，这些芯片已经被证明可以发射高达3THz的信号(尽管输出功率很低)；然后这些信号将由THzQC行波功率放大器放大。智能上的优点首先在于使用量子级联光子增益材料将BiCMOS型铸造电子学的性能扩展到1THz以上。由此产生的混合系统将展示出CMOS的优势(减小了体积和重量，提高了集成度和信号处理能力)，可产生高于1 THz的III-V量子级联激光器。其次，优点在于开发太赫兹硅互连结构，它将利用先进的芯片技术将BiCMOS和III-V芯片放置在接近微米级的对准精度，以实现低损耗太赫兹互连。这项研究涉及三个层面：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光谱)。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。

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.