Traveling-wave microwave switch using III-N gateless devices with capacitively-coupled contacts

In this work, we present a novel coplanar traveling-wave switch (CTWS) using Ill-nitride heterostructure device with capacitively-coupled contacts (C³). This type of contacts allows for low high-frequency contact impedance without using annealed/alloyed ohmic contacts. Turning the C³ HFET on and off can be achieved by applying the bias between the C³ and the channel using the control electrode outside the active region . Without the DC bias on the control electrode, both contacts are coupled with the 2-dimentional electron gas (2DEG) channel below, and the total device capacitance is high. When positive bias is applied to the control electrode and the potential difference between the contacts and the channel exceeds threshold voltage, the 2DEG channel beneath the contacts is depleted, which results in a very small total capacitance consisting of fringing capacitances only