Leakage Current Reduction in Planar AlGaN/GaN MISHEMT with Drain Surrounded by the Gate Channel

A new planar MISHEMT structure is proposed with the drain surrounded (D-S) by the gate channel. The gate channel serves as the stop-ring of the drain voltage, eliminating the damages from the high voltage on the mesa edge and isolation area. As a result, the leakage of the D-S MISHEMT is found to be reduced by almost 3 orders comparing with the source surrounded (S-S) MISHEMT. A saturated output current density of 740 mA/mm and an ON-resistance of 13.09 Omega.mm are obtained for device with LG/LGS/LGD/WC = 1.5/5/20/250 mu m. Meanwhile, the degradation of dynamic ON-resistance and off-state breakdown performance are investigated in both D-S and S-S MISHEMT, which indicates excellent reliability of the D-S MISHEMT.