The thermal management is an important issue for AlGaN/GaN high-electron-mobility transistors (HEMTs). In this work, the influence of the diamond layer on the electrical characteristics of AlGaN/GaN HEMTs is investigated by simulation. The results show that the lattice temperature can be effectively decreased by utilizing the diamond layer. With increasing the drain bias, the diamond layer plays a more significant role for lattice temperature reduction. It is also observed that the diamond layer can induce a negative shift of threshold voltage and an increase of transconductance. Furthermore, the influence of the diamond layer thickness on the frequency characteristics is investigated as well. By utilizing the 10-μm-thickness diamond layer in this work, the cutoff frequency fT and maximum oscillation frequency fmax can be increased by 29% and 47%, respectively. These results demonstrate that the diamond layer is an effective technique for lattice temperature reduction and the study can provide valuable information for HEMTs in high-power and high-frequency applications.

In this paper, the principle of discharge-based pulsed I-V technique is introduced. By using it, the energy and spatial distributions of electron traps within the 4-nm HfO 2 layer have been extracted. Two peaks are observed, which are located at ∆E ∼ −1.0 eV and −1.43 eV, respectively. It is found that the former one is close to the SiO 2 /HfO 2 interface and the latter one is close to the gate electrode. It is also observed that the maximum discharge time has little effect on the energy distribution. Finally, the impact of electrical stress on the HfO 2 layer is also studied. During stress, no new electron traps and interface states are generated. Meanwhile, the electrical stress also has no impact on the energy and spatial distribution of as-grown traps. The results provide valuable information for theoretical modeling establishment, material assessment, and reliability improvement for advanced semiconductor devices.