Search

The effect of the symmetries in the terahertz (THz) field distribution and the field-effect channel on THz photoresponse is examined. Resonant excitation of cavity plasmon modes and nonresonant self-mixing of THz waves are demonstrated in a GaN/AlGaN two-dimensional electron gas with symmetrically designed nanogates, antennas, and filters. We found that the self-mixing signal can be effectively suppressed by the symmetric design and the resonant response benefits from the residual asymmetry. The findings suggest that a single detector may provide both high sensitivity from the self-mixing mechanism and spectral resolution from the resonant response by optimizing the degree of geometrical and/or electronic symmetries. [ABSTRACT FROM AUTHOR]

Using only optical lithography, we have fabricated a GaN/AlGaN high-electron mobility transistor with distinctive source and drain antennas electrically isolated from the electron channel. Working at room temperature, it efficiently detects terahertz radiation via self-mixing, with a responsivity (3.6 kV/W) exceptionally high for a III-V device and with a noise [formula] just above the thermal limit. Performance improves at 77 K. While the device itself is micrometer-sized, our modeling indicates the asymmetric antennas induce a rather localized (<200 nm) region of strong self-mixing. Thus, a nanometer-scale active region is achieved by design and without recourse to electron-beam lithography. [ABSTRACT FROM AUTHOR]

This letter focuses on the fabrication and characterization of a terahertz detector integrated with a group of low pass filters and resonant antennas. The detector operates as a self-mixer on GaN/AlGaN high electron mobility transistor (HEMT). At room temperature, a strong dc photocurrent is produced with the aid of the antennas and filters. The responsivity of our HEMT device is estimated to be 53 mA/W and a noise equivalent power of [formula] can be achieved at 300 K. In addition, the sensor properties of a similar HEMT detector without filter are tested as a comparison. [ABSTRACT FROM AUTHOR]