A Novel Step-Doped Channel AlGaN/GaN HEMTs with Improved Breakdown Performance

The AlGaN/GaN high electron mobility transistor with a step-doped channel (SDC-HEMT) is first proposed in this paper. The potential distribution and the electric field (E-field) distribution of the device are explored by the numerical approach and analytical approach simultaneously. By introducing extra dopants to the channel layer, the E-field distribution along the AlGaN/GaN heterojunction interface is reshaped, resulting in an improved breakdown characteristic. An optimized doping concentration gradient of channel layer of 2 × 10¹⁶ cm^-3/step is proposed and verified by simulations. The breakdown voltage (BV) of the optimized SDC-HEMT reaches 1486 V with a 59.8% improvement compared with conventional AlGaN/GaN HEMT. In addition, the average E-field in the region between gate and drain improves from 1.5 to 2.5 MV/cm. Based on the equivalent potential method (EPM), an analytical model of the E-field and potential distribution is presented. The veracity and effectiveness of the proposed methodology is verified by the good agreement between the simulated and modeled results.