Nitride based transistors for millimeter wave operation

摘要

Field effect transistors having a power density of greater than 5 W/mm when operated at a frequency of at least 30 GHz are provided. The power density of at least 5 W/mm may be provided at a drain voltage of 28 V. Transistors with a power density of at least 8 W/mm when operated at 40 GHz at a drain voltage of 28 V are also provided. The transistors comprise:
a Group III nitride channel layer (16) of which are provided a spacer layer (62) and a gate contact (24) to modulate conductivity of the channel layer in response to a voltage applied to the gate contact;
source and drain contacts (20, 22) on the channel layer; and
a lower field plate (64) electrically connected to the gate contact and extending across the spacer layer a distance L FD of at least 0.1 µm towards the drain contact (22).