Over the past decades, the terahertz frequency regime (0.1-30 THz) has become the subject of much attention due to its wide range of applications in diverse areas such as astronomy, imaging, spectroscopy, communications, and so on. Although significant progress has been recently achieved, there is still a need for semiconductor devices efficiently operating at these frequencies. This project will provide in a short-timeframe an answer for a long-standing problem of the terahertz community: How to achieve very sensitive terahertz detection in foundry-friendly, large-scale manufacturable, solid-state devices at room temperature. To achieve this goal, the proposed work aims to exploit Super-Steep-Subthreshold-Slope Fin-based Field Effect Transistors as efficient terahertz detectors. This project will be the first to perform research on terahertz applications of this emerging transistor technology and is expected to transform the terahertz technology landscape in the coming years. Indeed, the expectation is to provide more than two orders of performance gain in terahertz detection, which is of immense interest to the terahertz community. More generally, harvesting the unique properties of emerging transistor technologies for viable real-world applications is also of high interest to the semiconductor device community. This research vision is interlaced with the strong educational objective of mentoring new generations of graduate and undergraduate students in the field of electron devices, high frequency electronics, analog circuits, terahertz, and optics, stimulating their critical thinking and curiosity by providing them with hands-on experience in cutting-edge research. This is of significant importance given the future projected needs for highly trained engineers and scientists in the United States.
This project aims at exploiting Super-Steep-Subthreshold-Slope Fin-based Field Effect Transistors as efficient terahertz detectors. The fundamental mechanism enabling a very sensitive terahertz response in these devices is their super-steep subthreshold slope (<10mV/dec.), which is a result of a positive feedback induced by weak impact ionization and can lead to a very large responsivity. Preliminary data based on the measured direct current characteristics of fabricated devices predicts a much better performance in terms of both responsivity as well as noise equivalent power with respect to all the existing current room-temperature terahertz detector technologies, i.e., noise equivalent power ~ 0.01 pW/(Hz^0.5). Super-steep-slope Field Effect Transistors will be fabricated and configured as ultra-high-performance terahertz detectors. Thanks to its super-steep-slope response, this technology can promise more than two orders of magnitude larger responsivity than the thermally-limited 10 A/W responsivity of room-temperature FET and Schottky diode terahertz detectors, without increase in cost. This level of performance is not achievable with regular CMOS technologies. Moreover, when compared with other promising post-CMOS transistor technologies as terahertz detectors (such as tunnel FETs), these devices constitute a more robust platform since: (a) room-temperature demonstrations of super-steep-slope field effect transistors with direct current performance according to the requirements of terahertz detectors have been already demonstrated, (b) super-steep-slope field effect transistors are silicon based and 100% compatible with CMOS processes.
