SLCFET Amplifier Performance Improvements Using an ALD TiN T-Gate Process

The super-lattice castellated field-effect transistor (SLCFET) is a multi-channel AlGaN/GaN HEMT device emerging as a technology platform for RF front ends, integrating world-class RF switches with high-performance RF amplifiers on the same wafer. This paper reports the performance results of a SLCFET amplifier device using an ALD TiN T-gate, which are improved with respect to previously reported data, with measured f t and f max up to 99 and 152 GHz respectively. The improvement is attributed to a reduced gate capacitance due to a higher T-gate hat without significant penalty of loss in gate control or increase of gate resistance. We also report W-band (94 GHz) large signal load-pull performance of the device with 4.33 W/active mm output power and 19.2% PAE. The process also demonstrates excellent DC/RF dispersion gate lag <1% and drain lag <2% and high breakdown voltage of 55 V.