Model-Based Prediction of the Plasma Oscillation Excitation Response Characteristics of a High-Electron Mobility Transistor-Based Terahertz Photomixer with the Cap Region

The model-based prediction of the response characteristics of a terahertz photomixer from the excitation of plasma oscillation in the channel of a high-electron mobility transistor (HEMT) with the cap region is presented in this paper. In the proposed model, the photo beam is inputted to the absorption layer of HEMT through the ungated area. Starting from the Euler equation and continuity equation, we obtained a response expression depicting the terahertz characteristics of that HEMT photomixer. As a result, the response as a function of the signal frequency is analyzed and the dependence of resonant frequency and amplitude on different length of cap region, voltage, and physical parameters are demonstrated. Are these may be useful for terahertz photomixer design and performance optimization.