Suppression of the DC-IV kink effect in AlGaN/GaN MIS-HEMTs through device topology variation

Abstract

This work investigates the DC-IV kink effect in AlGaN/GaN high-electron-mobility transistors (HEMTs) through structural variations in the gate–drain access length (Lgd) and the inclusion of gate field plates (GFPs). A linear trend between kink voltage (Vkink) and Lgd was observed over the measured geometry range, indicating that kink onset is strongly influenced by the gate–drain electric field. When expressed with respect to gate–drain voltage (Vgd), the kink voltage remained independent to gate bias, suggesting that the dominant traps contributing to the kink are located within the gate–drain access region. Devices with a GFP and Lgd = 15 μm exhibited complete suppression of the kink within the measured bias range, consistent with field redistribution reducing the local electric field required for field-assisted de-trapping. These findings provide insight into the field-dependent nature of the kink effect, consistent with Poole–Frenkel emission rather than hot-carrier or impact-ionization-assisted models. Furthermore, the findings show how targeted structural variations, such as gate–drain length and field plate design, can serve as practical diagnostic tools for locating and assessing trap-related behavior in AlGaN/GaN HEMTs. More broadly, the results highlight the importance of electric-field engineering and structural design in mitigating trap-related effects in GaN-on-Si devices.