Numerical Device Model for Reliable AlGaN/GaN HEMT Structure Design Based on Shear Stress

A numerical device model is proposed for the design of reliable AlGaN/GaN HEMT structures. In the model, shear stress due to the inverse piezoelectric effect is used to predict high-temperature DC stress test results. The calculated shear stress is compared with test results for various AlGaN/GaN HEMT structures. The comparison shows that structures passing the test have shear stress lower than 0.19 GPa under the test conditions. An AlGaN/GaN HEMT structure for the Ka band was designed so that stress would be lower than this value. The designed structure was fabricated and passed the test. These results indicate that the model can be used to design reliable AlGaN/GaN HEMT structures.