AlGaN/GaN/AlGaN DH-HEMTs Breakdown Voltage Enhancement Using Multiple Grating Field Plates (MGFPs)

GaN-based high-electron mobility transistors with planar multiple grating field plates (MGFPs) for high-voltage operation are described. A synergy effect with additional electron channel confinement by using a heterojunction AlGaN back barrier (BB) is demonstrated. Suppression of the off -state subthreshold gate and drain leakage currents enables breakdown voltage enhancement over 700 V and a low on-state resistance of 0.68 $ \hbox{m}\Omega \times \hbox{cm}^{2}$. Such devices have a minor tradeoff in on-state resistance, lag factor, maximum oscillation frequency, and cutoff frequency. A systematic study of the MGFP design and the effect of Al composition in the BB is described. Physics-based device simulation results give insight into electric field distribution and charge carrier concentration, depending on the field plate design.