Analysis of MIS-HEMT Device Edge Behavior for GaN Technology Using New Differential Method

A new differential method for accurate extraction of electrical parameters of high-electron mobility transistor (HEMT) devices for gallium nitride (GaN) technology is proposed. This method, presented here for the first time, is used to study the mobility degradation with gate length, allowing an analysis of the contribution of the gate edge region to the total metal-insulator semiconductor (MIS)-HEMT device conductance. First, an analytical model is proposed to account for the relative conduction of the edges and the main flat part of the channel HEMTs. Second, the differential method allows the split-CV mobility extraction of each part, allowing a precise analysis of the resistive contribution of each region of the HEMT devices. This study has been performed over a large range of channel lengths for two normally OFF HEMT GaN wafers having different recess depths.