Plasmonic Boom Terahertz Source
Abstract
The goal of this project is to design and characterize high power terahertz (THz) grating gate sources and detectors based on the new idea of plasmonic boom. To achieve this goal, we will meet the following objectives ¥ Develop two-dimensional theory of the plasmonic boom transistors ¥ Develop the theory of the plasmonic boom accounting for collisions with impurities and scattering by lattice vibrations and boundaries ¥ Evaluate wireless communication using plasmonic boom detectors and sources will propose and investigate a new mechanism that should enable powerful but compact THz electronic sources. The idea is to accelerate electrons in device channels and modulate the electron velocity in a periodic nanostructure in such a way that the electron drift excites the waves of the electron density (plasma waves). The electron drift velocity in a variable width gated structure (see Figure 3) will periodically exceed the plasma wave velocity and then will drop back below the plasma wave velocity. What happens in this situation is very similar to the Òsonic boomÓ occurring when a jet crosses the sound barrier. However, in these device structures the Òplasmonic boomÓ occurs over and over, and the periodic structure itself serves as an antenna to couple out the terahertz radiation that is generated by these repeated Òplasmonic boomsÓ. Further enhancement of the instability occurs due to the resonant excitation of the unstable plasma modes under the super resonance condition when all plasma modes in the plasmonic crystal formed in the channel become unstable. Another advantage of this approach (compared to more conventional single device detectors) is that the plasmonic crystal efficiently couples with THz electromagnetic radiation and can also be used for detection of the THz radiation. The modern silicon VLSI commercial fabrication techniques reached a feature size of 10 nm in 2015, which is smaller than the mean free path in Si at room temperature (~ 30nm). This makes the ballistic plasmonic crystal analysis to be realistic as the first approximation at room temperature and to be a very good approximation at cryogenic temperatures. High values of the electron mobility in graphene (up to 200,000 cm2/V-s at room temperature) make this material a good candidate for the THz plasmonic crystal application. Applications of terahertz sensing technology range from radio astronomy and earth remote sensing to non-destructive testing of VLSI, chemical analysis, explosive and mine detection, concealed weapons detection, moisture content determination, film uniformity and coating thickness control, structural integrity testing, and medical and biological applications. The proposed THz generation mechanism should enable a new generation of efficient and compact THz sources. Our estimates for a 1 micron long, 10 micron wide device with 5 periods of the grating gate predict the output power at 1 THz close to 100 mW. When the asymmetry is introduced into this system (either by design of by tilting the THz beam with respect to the normal to the sample surface), the structure could be used as a THz detector and matching coupled sources and detectors could be used for testing chemicals and biological fluids deposited. This research technique and research results of the project is to be incorporated in to the course material on advanced and introductory electronics taught by PIs.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 15, 2018
- Source ID
- W911NF1710471
Entities
People
- Michael Shur
Organizations
- Army Contracting Command
- Rensselaer Polytechnic Institute
- United States Army