A Novel Si–GaN Monolithic Integration Technology for a High-Voltage Cascoded Diode

In this letter, a novel approach for monolithic integration of Si-based and GaN-based devices on Si substrate for high-voltage power switching applications is reported. To enable the integration, AlGaN/GaN epitaxial growth is carried out in recessed windows on a Si (111) substrate by selective epitaxial growth. A cascoded diode formed by series connection of a Si diode and a normally-ON AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistor is experimentally demonstrated by using this technology. The cascoded diode features a breakdown voltage of 557 V and a differential specific ON-resistance of 2.8 mΩ· cm2 at 500 A/cm2. Its reverse leakage current is two orders of magnitude lower compared with the conventional AlGaN/GaN Schottky barrier diode. The characterization results of the fabricated cascoded diode demonstrate that the proposed Si-GaN monolithic integration technology is compatible with both Si and GaN fabrication processes.