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

Huili (Grace) Xing, T. Zimmermann, D. Deen, K. Wang, C. Yu, T. Kosel, P. Fay, and D. Jena
Department of Electrical Engineering,
University of Notre Dame, Notre Dame, IN 46556, USA
(Email: hxing@nd.edu, Phone: 574 631 9108)
Keywords: GaN, AlN, HEMT, MBE, RF, Mobility

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.
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