Vertical GaN-on-Si MOSFETs With Monolithically Integrated Freewheeling Schottky Barrier Diodes

We demonstrate for the first time the monolithic integration of vertical GaN MOSFETs with freewheeling Schottky barrier diodes (SBD), based on a 6.7-mu m-thick n-p-n heterostructure grown on 6-inch silicon substrates by metal organic chemical vapor deposition. The anode of the SBD is integrated in the source pad of the MOSFET and the cathode is directly connected to the MOSFET drain through the bottom n(+)-GaN layer, eliminating the need of any metal wire interconnection. This monolithic integration scheme offers reduced footprint, minimized parasitic components, and simplified packaging. The integrated MOSFET-SBD showed enhancement-mode operation with a threshold voltage of 3.9 V, an ON/OFF ratio of over 108 and a dramatic improvement in reverse conduction, without degradation in on-state performance from the integration of the SBD. The integrated GaN-on-Si vertical SBD exhibited excellent performance, with a specific on-resistance of 1.6 m Omega.cm(2), a turn-on voltage of 0.76 V, an ideality factor of 1.5, along with a breakdown voltage of 254 V.