Self-Switching Nanodiodes for Generation and Detection of THz Radiation, Research Area 11 (STIR), Research Area 4(Electronics 4.1)
Abstract
The terahertz (THz) region of electromagnetic radiation spectrum has been called a ÒTHz Gap,Ó since it lies between optics and radio-frequency engineering and is difficult to access with either technology. Recently, the THz frequencies have received great international interest due to their unique applications ranging from ultrafast local wireless communications, through quality control and security screening, to medical diagnostics and biosensing imaging. The reason is that many materials are transparent to THz waves and, at the same time, most organic molecules have unique signatures in THz radiation absorption, resulting in their easy, noninvasive identification. For living organisms, THz radiation is much safer than X rays. In spite of the enormous technological efforts, the THz gap is still not covered. Simply reducing the device length in electronic structures is not enough to increase their operating frequency to the THz region, while for photonic devices energy of THz radiation quanta is too small for optical characterization methods. We investigate a new class of nanostructures, the self-switching diode (SSD), as an emitter and detector of THz radiation. The SSD operates on a new mechanism whereby it obtains rectification, not from energy barriers such as those in p-n junctions, but from its asymmetric nanostructure and lateral field effect. Thus, it is an intrinsic nanostructure, since a larger version would not exhibit nonlinearity. The SSD nano-dimensions enable picosecond electron transit times and ultra-low capacitance, thereby enabling response at THz frequencies. Another important advantage of this nano-diode is its simple planar structure, ease of fabrication, and ability to integrate with THz antennas. This proposed program involves fundamental exploration of new device physics and materials science operating in the nanoscale, which will lead to efficient THz generation and detection systems operating at room temperature. Our research has a strong foundationÐour preliminary studies and our research expertizeÐand is fundamental in nature, but with an applied flavor. We start with design and fabrication of both 2-dimensional electron gas and bulk-doped semiconductor nano-channels based on III-V heterostructures custom grown by molecular beam epitaxy in Prof. WicksÕ laboratory. Next, we move to our in-house device nano-patterning using either electron-beam lithography and plasma etching, or focused ion beam cutting (URnano Facility) and, subsequently, continue with exhaustive DC device characterization. Finally, we perform time-resolved, subpicosecond (THz bandwidth) testing of optically gated SSDs in Prof. SobolewskiÕs laboratory, as well as implement our SSDs as either generators or detectors in our THz time-resolved spectroscopy system.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510356
Entities
People
- Roman Sobolewski
Organizations
- Army Contracting Command
- United States Army
- University of Rochester