GaN-based Tri-gate high electron mobility transistors

The rapidly-growing data throughput rates in a wide range of wirelesscommunication applications are pushing the established semiconductordevice technologies to their limits. Considerably higher levels of solidstateoutput power will therefore be needed to meet the demand in thenext generation satellite communications as well as the RADAR systems.Owing to their superior material properties such as high breakdown fieldsand peak electron velocities, GaN-based high electron mobility transistors(HEMTs) have recently prevailed in high-power systems operating in themicrowave frequency bands. On the other hand, technologies based onGaAs or InP still make up a large portion of the state-of-the-art devices and circuits at the millimetre-wave (MMW) and sub-MMW frequencies.Due to the strong dependence of the intrinsic device parameters on the applied bias point, highly-scaled GaN HEMTs are prone to experiencing deteriorated high frequency characteristics which severely limit the high power performance as well. Here, the relatively poor control of the gate electrode is known to be the underlying root of the performance drop. In an attempt to overcome this by means of reinforcing the gate-control, 3-dimensional GaN HEMT devices featuring the Tri-gate topology are developed in this work, exhibiting enhanced performance in terms of bothoff- and on-state figures of merit.