Physics based simulation for studying the impact of contact resistance on DC & RF characteristics of AlGaN/AlN/GaN HEMT

Formation of a two-dimensional electron gas (2DEG) in AlGaN/AlN/GaN heterostructures plays a vital role in high power and high frequency device technology. Such kinds of heterostructures are used for the fabrication of High Electron Mobility Transistors (HEMTs). Ohmic contacts to AlGaN/AlN/GaN based heterostructures with low contact resistance and smooth surface are crucial in the development of high power, high frequency transistors in the GaN system. In the present study, physics based simulation of impact of ohmic contact resistance on DC and RF characteristics of AlGaN/AlN/GaN HEMT on 6H-SiC substrate has been addressed for the first time.Three samples, A, B and C of contact resistance 0.25, 0.27 and 0.59 □*mm respectively were fabricated with different process variations. By using measured contact resistance values, physics based simulation of 100nm gate length GaN HEMT was done and corresponding device behavior was studied using TCAD. It has also been shown that simulated results for AlGaN/AlN/GaN heterostructure are closely matching with reported measured data.