A normally-off fully AlGaN HEMT with high breakdown voltage and figure of merit for power switch applications

• Novel normally off fully AlGaN HEMT is presented.
• The AlGaN channel increases the breakdown voltage of 598 V.
• The p-type AlGaN gate facilitates the normally-off operation.
• The proposed structure shows moderately low ON-resistance of 143.71 mΩ mm2.

In this paper, we propose a fully AlGaN high electron mobility (HEMT) in which the gate electrode, the barrier and the channel are all AlGaN. The p-type AlGaN gate facilitates the normally-off operation to be compatible with the state-of-the-art power amplifiers. In addition, the AlGaN channel increases the breakdown voltage (VBR) to 598 V due to the higher breakdown field of AlGaN compared to GaN. To assess the efficiency of the proposed structure, its characteristics are compared with the conventional and recently proposed structures. The two-dimensional device simulation results show that the proposed structure has the highest threshold voltage (Vth) and the VBR with the moderately low ON-resistance (RON). These features lead to the highest figure of merit (2.49 × 1012) among the structures which is 83%, 59%, 47% and 49% more than those of the conventional, with a field plate, AlGaN gate and AlGaN channel structures, respectively.