Physics-Based Simulation for Studying the Impact of Contact Resistance on DC and RF Characteristics of AlGaN/AlN/GaN HEMT

Formation of a two-dimensional electron gas 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. Samples A, B, and C of contact resistance 0.25, 0.27, and 0.59 omega * mm, respectively, were fabricated with different process variations. By using measured contact resistance values, physics-based simulation of 100-nm 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.