Microwave and power characteristics of AlGaN/GaN/Si high-electron mobility transistors with HfO2and TiO2passivation

This work presents AlGaN/GaN high-electron mobility transistors (HEMTs) that are grown on silicon. Various passivation layers are deposited on AlGaN / GaN HEMTs. AlGaN/GaN HEMTs were fabricated with TiO 2 dielectrics, and their performance was compared with that of unpassivated and that of HfO 2 -passivated HEMTs. The TiO 2 -passivated HEMT with a gate length of 1 μ m exhibits a maximum extrinsic transconductance of 134.4 mS mm −1 , a current-gain cutoff frequency of 10.62 GHz, and a maximum frequency of oscillation of 16.37 GHz. Capping with any of the dielectric materials used herein improves the device performance over that of the unpassivated HEMTs. Additionally, experimental data demonstrate that the use of TiO 2 is a favorable alternative to HfO 2 passivation. This work is the first to present the microwave power of TiO 2 -passivated AlGaN/GaN HEMTs.