An AlGaN/GaN HEMT by the periodic pits in the buffer layer

Abstract

In this paper, an AlGaN/GaN high electron mobility transistor (HEMT) by the periodic pits in the end of the buffer layer (PPB-HEMT) is proposed. The main focus of this proposed structure is based on controlling the carrier concentration and uniformity of the electric field distribution in the two dimensional electron gas (2DEG) channel layer that improves the breakdown voltage. The carrier concentrations fall under the gate by making periodic pits in the end of the buffer layer in the PPB-HEMT structure. Then, the electric field value reduces across the 2DEG channel layer and the electric field obtains the critical value at a higher drain-source voltage. Accordingly, the breakdown voltage of the PPB-HEMT improves approximately 32% compared to a conventional HEMT (C-HEMT). Consequently, the maximum output power density of the PPB-HEMT increases by 21% compared to the C-HEMT. Also, the depletion region width across the channel under the gate increases in the PPB-HEMT, and the gate-drain capacitance of the proposed structure decreases by 77% compared to the conventional structure. Therefore, the cut-off frequency of the PPB-HEMT improves by 50% compared to the C-HEMT due to the reduction in gate-drain capacitance. In addition, the current gain, unilateral power gain, and the maximum available power gain of the proposed structure increase. Therefore, the use of PPB-HEMT is more appropriate than the C-HEMT in high power and high frequency applications.