Analysis and simulation of bulk polarization mechanism in p-GaN HEMT with AI component gradient buffer layer

In this paper,bulk polarization mechanism and radiation simulation of the Al component gradient buffer layer (GBL) and constant buffer layer (CBL) of p-GaN HEMT (p-GaN GBL-HEMT and p-GaN CBL-HEMT) are analyzed and studied. It is found that the p-GaN GBL-HEMT can significantly reduce the buffer leakage current. The linear gradient amplitude (the range of linear gradients of Al components vertically in the buffer) of 20~30% Al components can significantly increase the breakdown voltage (VBK) of the device, up to 1312V. Simultaneously, although the p-GaN GBL-HEMT reduces the 2DEG concentration, the device still has a specific on-resistance (RON,sp) and drain saturation current (IDS,sat) equivalent to the p-GaN CBL-HEMT due to the conductivity modulation effect. Its Baliga figure of merit is up to 2.27 GW/cm2. Finally, through the SEE simulation and the bulk polarization mechanism analysis, it is found that the drain transient current (IDS,trans) by the identical incident particles in the p-GaN GBL-HEMT is lower than that in the p-GaN CBL-HEMT, and the IDS,trans decreases with the increase of the Al components gradient amplitude. Therefore, the p-GaN GBL-HEMT provides a new idea for improving the electrical performance and SEE hardening.