Numerical Investigation of GaN HEMT Terahertz Detection Model Considering Multiple Scattering Mechanisms

Abstract

GaN high-electron-mobility transistor (HEMT) terahertz (THz) detectors have been widely studied and applied in the past few decades. However, there are few reports about the influence of GaN/AlGaN heterostructure material properties on the detection model at present. In this paper, a response voltage model for a GaN HEMT THz detector that considers the carrier scattering in a GaN/AlGaN heterostructure is proposed. The phonon scattering, dislocation scattering, and interface roughness scattering mechanisms are taken into account in the classic THz response voltage model; furthermore, the influence of various material parameters on the response voltage is studied. In a low-temperature region, acoustic scattering plays an important role, and the response voltage drops with an increase in temperature. In a high temperature range, optical phonon scattering is the main scattering mechanism, and the detector operates in a non-resonant detection mode. With an increase in carrier surface density, the response voltage decreases and then increases due to piezoelectric scattering and optical phonon scattering. For dislocation and interface roughness scattering, the response voltage is inversely proportional to the dislocation density and root mean square roughness (RMS) but is positively related to lateral correlation length. Finally, a comparison between our model and the reported models shows that our proposed model is more accurate.

Multi‐Subband Polar Optical Phonon Scattering in InAlN/AlN/GaN Heterostructures

“…For instance, a simplified multi-subband POP scattering model replaces the second square bracket in Equation ( 8) with ð1 À cos θÞ to simplify the contribution from in-scattering processes, resulting in a closed-form momentum relaxation time. [12][13][14][15] The frequently used single-subband POP scattering uses the quantum limit approximation, which assumes that only the lowest subband is occupied by electrons and ignores the impact of higher subbands occupation on electron transport. [9][10][11] The validity of the two simplified models will be evaluated.…”

“…[9][10][11] Other studies simplified the in-scattering processes to avoid the iterative numerical calculation process. [12][13][14][15] Others used approximate analytic expressions for mobility to describe the POP scattering. [16][17][18] The predictions of these simplified models often differ greatly.…”