Ultrathin all-binary AlN/GaN based high-performance RF HEMT Technology

AlN/GaN HEMTs offer a number of performance improvements over traditional AlGaN/GaN structures. In this work, the epitaxial growth and characterization of of AlN/GaN heterostructures by MBE is shown to lead to record low channel sheet resistances, lower than 150 Ohms/square. The DC performance of the resulting HEMTs on sapphire substrates shows that current densities in excess of 2 A/mm and transconductances larger than 400 mS/mm can be routinely obtained in such HEMTs. Preliminary high-frequency characterization of the binary HEMTs shows that by virtue of the reduction of access resistances, very high frequency performance is achievable. Alloy-free AlN/GaN heterostructure technology offers a number of critical advantages over competing AlGaN/GaN and AlInN/GaN technologies for vertical and lateral scaling to push the high-frequency limits of nitride HEMTs