3D simulation of impact ionization induced kink effect in AlGaN/GaN HEMTs: A novel split channel design with asymmetric double gate for kink suppression

In this paper, we present 3D simulation of AlGaN/GaN High Electron Mobility Transistors (HEMTs) to demonstrate impact ionization generated kink effect on current-voltage characteristics. We use an in-house built self-consistent simulator coupled with impact ionization model to obtain kink voltage and total drain current by iterations. Dependence of kink voltage on applied gate bias is also studied. From the results, we suggest a simple technique to suppress kink effect by reducing Al mole fraction. However, this technique has a trade-off that it reduces electron mobility too, making the device inappropriate for high frequency applications. Finally, a novel asymmetric double gate design with split channel is proposed. It is shown that the design effectively suppresses kink effect with no need to reduce mole fraction or electron mobility. The proposition would be useful in designing kink-free devices suitable for high frequency applications.