This integrated research and education plan investigates a new family of plasmonic devices for tunable detection of THz radiation at room temperature through systematic theoretical and experimental study of plasmon-THz electromagnetic radiation interactions in complex nano-scale Field Effect Transistor (FET) structures. The proposed multi-element plasmonic devices will have very high speed and high responsivity at room temperature with wide range of continuous tunability by DC bias. To reach the stated goal a holistic approach with its theory, demonstration, implementation, education and dissemination will be adopted with the following major tasks: (1) Theoretical study of 2D electron gas plasmons-THz radiation interactions in a) single-channel multi-gate FET structures and b) multi-channel FET structures. (2) Design, fabrication and extensive characterization of resonant absorption and photoresponse characteristics of the proposed devices to demonstrate room temperature tunable detection of THz radiation. (3) Implementation of the proposed devices for engineering applications including THz focal plane array imaging sensors and THz biological and chemical sensors with integrated microfluidic channels. (4) Integration of K-20 education and underrepresented groups into research activities.
Intellectual Merit: THz technology has potential applications in medicine, biology, chemistry, security, and space. Many of these applications require spectral selectivity. However lack of tunable sources and detectors necessitates the use of complex methods (e.g. heterodyne detection) or bulky optical components for frequency selection. Despite their impressive responsivity levels, conventional THz detectors are not tunable or suitable for portable applications. The PI proposes a transformative plasmonic device technology which could lead the first tunable direct detectors operating at room temperature. The proposed devices are micro/nano-scale semiconductor devices which can be easily integrated with semiconductor electronics. With their tunable resonant absorption characteristics, proposed plasmonic devices can also be used as very fast tunable filters for other THz detection methods. These advantages will pave the way for THz-spectrometer-on-chip. The proposed research will also result in a thorough understanding of the THz electromagnetic radiation-plasmon interactions in complex FET structures which have not been fully understood yet and will expand our knowledge in the science of plasmonics. Analytical and numerical models which will be developed and tested will also help to create other novel devices such as tunable plasmonic THz sources, photomixers, and plasmonic crystals with nanoscale resonance elements such as quantum dots and plasmonic nanowires. Development of efficient coupling and conversion techniques for THz radiation can also make energy harvesting possible in far infrared and THz range of the electromagnetic spectrum which is currently not exploited as a widely available renewable energy source.
Broader Impact: The integration of experimental effort along with theoretical analysis will offer invaluable experiences to graduate and undergraduate students at Florida International University and create synergy between departments of Electrical & Computer Engineering, Biomedical Engineering and College of Medicine leading new applications for the proposed device technology. A complementary education plan will develop a program for disseminating knowledge of the advancements in THz technology and nanotechnology into high school and university classrooms. It will include an outreach to K-12 students in a predominantly underprivileged and socio-economically impacted neighborhood of Miami, FL. Several undergraduate students from the diverse population of FIU will be actively involved with the proposed research activities. Education component also includes supervising two graduate students and development of a graduate course on THz technology and applications. Proposed plan will enhance the research infrastructure for the scientific communities at FIU and in south Florida by supporting the FIU THz Research Lab. Building on existing strengths and closely working with these communities; the PI will make the services developed within this proposal available to researchers across the nation. The PI is also planning to increase the impact of this work via international technical workshops, and an edited book in this area. In the long run, development of tunable THz detectors will simplify the THz imaging and detection systems by eliminating necessity of these complex frequency selection apparatus and/or tunable sources. Therefore the proposed devices have the potential of bringing an abundance of THz applications into life such as security and medical imaging, biochips, chemical and biological sensing and DNA analysis as part of a long-term research and possible commercialization opportunities.
