A semi-floating gate AlGaN/GaN HEMT for normally-off operation

Abstract

AlGaN/GaN-Si based HEMTs are considered as the promising candidates for application in the 5G communication system due to their excellent characteristics and low cost. Enhancement mode (E-mode) AlGaN/GaN HEMTs should be fabricated for power application. In this paper, we report a novel semi-floating gate (SFG) AlGaN/GaN HEMT with 20 nm Al2O3 which acts as control gate capacitance for normally-off operation. This methods avoids gate recess process which may damage the 2DEG channel. Also, the Vth can be programmed to different values by adjusting the VCGP. In our results, by adjusting control gate voltage VCGP = 15 V, the Vth of AlGaN/GaN HEMT on PCB (containing capacitances with different capacitance values which acts as control gate capacitance) is extracted to exceed over 8.5 V at VDS = 15 V. In addition, for the fabricated SFG AlGaN/GaN HEMT with the Al2O3 thickness of 20 nm, the Vth of the fabricated SFG AlGaN/GaN HEMT is extracted to be 0.42 V when VCGP increases up to 5 V. The SFG AlGaN/GaN HEMT technique presented in our results offer a prospective method to fabricate E-mode AlGaN/GaN HEMTs.