High-power RF switching using III-nitride metal-oxide-semiconductor heterojunction capacitors

We propose and demonstrate a novel III-Nitride high-power robust RF switch using SiO₂-AlGaN-GaN metal-oxide-semiconductor heterojunction (MOSH) capacitors. A metal electrode deposited on the top of the SiO₂ layer and the low-resistivity two-dimensional electron gas (2DEG) channel at the AlGaN-GaN interface serve as the MOSH capacitor plates. Two "back-to-back" connected MOSH capacitors form a double MOSH (D-MOSH) RF switch thereby eliminating the need for ohmic contacts and also allowing fully self-aligned fabrication. The D-MOSH switch has a symmetrical π-type capacitance-voltage characteristic with a static ON-OFF capacitance ratio greater than 20:1. The RF switch exhibits similar polarity independent sharp π-type transmission bias curve. At 2GHz, a single-element multifinger D-MOSH switch shows isolation greater than 25 dB and insertion loss of 0.7 dB. The switching power exceeds 60 W/mm making the novel D-MOSH switch robust device for high-power high-temperature integrated electronics.