Normally-off GaN recessed-gate MOSFET fabricated by selective area growth technique

In this letter, a normally-off GaN recessed-gate MOSFET is demonstrated using a nonplasma gate recess technique, in which the access region with AlGaN/GaN heterostructure was selectively grown on a semi-insulating GaN/Si template to naturally form a recessed gate. The normally-off recessed-gate Al 2 O 3 /GaN MOSFET presents a high threshold voltage of 3.5 V and a maximum drain current density of 550 mA/mm (at a positive gate bias of 12 V). A maximum field-effect mobility of 170 cm 2 V −1 s −1 and a large on/off current ratio of more than 10 7 was obtained, which indicates the high quality of the Al 2 O 3 /GaN interface.