Triple tooth AlGaN/GaN HEMT on SiC substrate: A novel structure for high-power applications

Abstract

In this paper, a AlGaN/AlN/GaN/SiC High Electron Mobility Transistor (HEMT) to reduce the electric field is suggested. The main idea of this work is to improve the Direct Current (DC) and Radio Frequency (RF) properties of device by modifying the depletion region in the channel. The proposed structure consists of a floating metal like a comb with triple tooth which is located in the space between the gate and drain and inside the buffer layer. We called the proposed structure as triple tooth HEMT (TT-HEMT). The RF and DC characteristics of the proposed structure are studied using numerical simulations. The breakdown voltage (V BR ) increases to 169.5 V for the proposed structure in comparison with 103 V for the conventional HEMT (C-HEMT) due to the modified electric field distribution in the channel of the TT-HEMT structure. The maximum output power density (P max ) of the TT-HEMT structure is 60.4% greater than that of the C-HEMT. The optimized results show that the maximum oscillation frequency (f max ) and cut-off frequency (fT) of the proposed structure improve 111% and 26.5%, respectively compared to the C-HEMT structure. In addition, the maximum available gain (MAG) of the TT-HEMT structure is obtained 8.5 dB higher than that of the C-HEMT structure at the frequency of 40 GHz. The optimal results show that whatever the number of teeth on metal increases, the depletion region in the channel is modified more and the breakdown voltage increases, as well. Besides, the output power density (P max ) is improved with the increasing number of teeth on metal (N). This characteristic is also true, for the cut-off frequency (f T ), the maximum oscillation frequency (f max ) and the maximum available gain (MAG) of the proposed structure. However, the drain current (I D ) of the proposed structure is reduced.