Effect of Source-Connected Field Plate on Electric Field Distribution and Breakdown Voltage in AlGaN/GaN HEMTs

Electric field distribution in the channel and breakdown characteristics of an AlGaN/GaN HEMT with a source-connected field plate (SC-FP) were investigated using a two-dimensional device simulation. The analysis of electric field distribution and breakdown voltage varying with the changes of the insulator thickness t and the field plate length LFP revealed that to maximize the breakdown voltage, t has to be increased to make the peak electric field at drain side of gate edge approaching breakdown electric field and LFP be long enough to prevent the high-field region at gate edge and that nearby FP edge from overlapping. For the simulated device, optimum t is about 0.2mum and LFP around 2.2mum, from which a breakdown voltage 365V was obtained