Numerical modeling of highly sensitive resonant detection of THz radiation using a multichannel dispersive plasmonic HEMT

The resonant detection of terahertz radiation using a dispersive AlN/GaN multichannel high-electron-mobility transistor (HEMT) is analyzed and modeled in this paper. The proposed full-wave model is based on the concurrent solution of the complete hydrodynamic model (CHM) and Maxwell’s equations. The CHM is derived from the first three moments of the Boltzmann transport equation (BTE). Considering the variations of the electron temperature and transport parameters along the HEMT channel, this model well characterizes the electron–wave interaction in the device for both low- and high-field conditions. Moreover, the effect of the optical phonon modes of the GaN buffer, which cannot be ignored in the target terahertz frequency band, is described using the Lorentz dispersive model. Employing the developed model, the transmission spectrum of the device is extracted numerically using the finite-difference time-domain (FDTD) method for grating-gate single-, double-, and three-channel HEMT structures. The results show that, at a lattice temperature of 300 K for a GaN grating-gate HEMT with gate periodicity of 680 nm and gate width of 520 nm, at given resonance frequency and overall electron concentration, the resonance depth improves by about 2.7 dB in the three- compared with the single-channel structure. Moreover, it is shown that the detection performance of such a structure at 300 K is similar to the single-channel HEMT at a reduced temperature of 120 K. Therefore, the multichannel HEMTs can show notably improved resonant detection performance, enabling the design of resonant detectors with enhanced sensitivity at room temperature.