We report on recent progress on the development of Scandium Aluminum Nitride (ScAlN) based heterostructure field effect transistors (HFETs). We are leveraging the enhanced polarization properties of ScAlN lattice-matched to Gallium Nitride (GaN) to produce heterostructures that support very large carrier densities (>3.0×10 13 /cm 2 ). We have successfully grown device-quality ScAlN/GaN heterostructures by molecular beam epitaxy (MBE). Using these wafers we have fabricated low resistance contacts for ScAlN barrier HFETs and demonstrated transistors which simultaneously achieve high current density (>3 A/mm), large breakdown voltage (>60 V), and good mm-wave small signal gain (>13 dB at 30 GHz). The high current density coupled with the large breakdown field strength of GaN enables both current and voltage scaling of ScAlN/GaN HFETs and enables design of transistors that overcome the Bode-Fano bandwidth limitations.