Localized buried P-doped region for E-mode GaN MISHEMTs

A new design for an enhancement mode Gallium Nitride based high electron mobility transistor is proposed along with a novel fabrication technique. Normally-off operation is achieved through the introduction of a localized p-region below the AlGaN/GaN interface underneath the gate electrode. Since achieving high hole concentration through ion implantation is experimentally challenging, the effect of a localized buried p-region was replicated through the growth of an epitaxial p-layer in which N-wells will be later introduced. Simulation results conducted under ATLAS, a TCAD simulation tool from Silvaco, demonstrated a successful shift of the threshold voltage to positive values. The physics behind this shift is explained through the band diagram. A sensitivity analysis is conducted showing the effect of device parameters on the threshold voltage and the current density.