Investigation of Nano-Heat-Transfer Variability of AlGaN/GaN-Heterostructure-Based High-Electron-Mobility Transistors

The aim of this work is to propose an electrothermal model for predicting the electron mobility, the effective thermal conductivity, and the operating temperature of AlGaN/GaN HEMT devices. The suggested model comprises an enhanced ballistic-diffusive model (BDE) coupled with a drift-diffusion model (D-D). Furthermore, the given model considers total electron mobility, which depends on mobility degradation caused by phonon interactions, surface imperfections, and carrier mobility inside the bulk GaN material. The model is validated based on available experimental and numerical results, and good concordance is observed. It is found that the degradation of the drain current is due to electron mobility and effective thermal conductivity degradation. The output characteristic's degradation due to changing device temperature is analyzed. We demonstrate that for gate biases of -1 V, 0 V, and 1 V, operating temperatures of 390 K, 470 K, and 570 K are obtained when the drain currents are 0.1 A, 0.24 A, and 0.38 A, respectively. Furthermore, we demonstrate that the temperature is maximal in the active region. The temporal temperature evolution presents the same trends with the same amplitude compared to the experimental data, and the error does not exceed 5%.