Analysis of surface charging effects in passivated AlGaN-GaN FETs using a MOS test electrode

Passivated AlGaN-GaN high electron mobility transistor (HEMT) structures are modified by adding a MOS test gate placed between gate and drain to identify surface charge phenomena by stress experiments. A new method is described to identify the vertical position of the charge centroid of charge injected from the gate. In the case investigated, this is within the passivation layer.