A Novel 700 V Monolithically Integrated Si-GaN Cascoded Field Effect Transistor

In this letter, a novel monolithically integrated Si-GaN cascoded FET is designed and experimentally demonstrated for high-voltage power switching applications. The device is formed by monolithically connecting a low-voltage Si MOSFET and a high-voltage normally-on GaN MIS-HEMT on the same substrate in the cascode configuration. The interconnection distance is 50 μm which is only 2.5% of that of the conventional two-chip co-package approach (~2 mm). The fabricated cascoded FET features normally-off functionalities with a threshold voltage of 3.2 V, a drive current of 1850 A/cm2 (630 mA/mm) at the gate bias of 15 V, a gate swing of 20 V, a specific on-resistance of 3.3mΩ⋅cm2 and a breakdown voltage of 696 V.