Advances in the Super-Lattice Castellated Field Effect Transistor (SLCFET) for High Power Density, Energy Efficient RF Amplification

Efficient, high power density RF signal amplification is a driving enabler for future RF systems. The Super-Lattice Castellated Field Effect Transistor (SLCFET) leverages a GaN-based superlattice to support multiple stacked 2D-┬ČElectron Gas (2DEG) layers, thereby increasing its charge density compared to conventional GaN transistors by as much as 10x, directly boosting output power density. The low sheet resistance of the stacked 2DEG superlattice layers lowers device contact and source resistances, resulting in a low knee voltage. In addition, the SLCFET uses a three-dimensional, low resistance gate electrode to maintain healthy device electrostatics, high output resistance, and low input resistance. The SLCFET RF amplifier provides record-setting output power density at mmW frequencies with excellent power-added-efficiency and linearity. Measured transistor values show excellent potential for both power and low noise amplification applications. With IDS >2.4A/mm, fT=50GHz, fmax=100GHz, we demonstrate Pout= 9.5W/mm, PAE = 41%, and OIP3/P1dB =14dB at 30GHz.