AlN/Al<sub>0.5</sub>Ga<sub>0.5</sub>N HEMTs with heavily Si-doped degenerate GaN contacts prepared via pulsed sputtering
Ryota Maeda, Kohei Ueno, Atsushi Kobayashi, Hiroshi Fujioka
Abstract
Abstract This paper reports AlN barrier Al 0.5 Ga 0.5 N high electron mobility transistors (HEMTs) with heavily Si-doped degenerate GaN contacts prepared by pulsed sputtering deposition. Selectively regrown n-type GaN contacts exhibit typical degenerate properties with the electron concentration and mobility of 2.6 × 10 20 cm −3 and 115 cm 2 V −1 s −1 , respectively, resulting in a record low contact resistance R C of 0.43 Ω mm for the AlN/Al 0.5 Ga 0.5 N HEMTs. The AlN/Al 0.5 Ga 0.5 N HEMTs displayed a remarkable DC output characteristic with a maximum drain current density of 250 mA mm −1 , a transconductance of 32 mS mm −1 , and an On/Off ratio >10 6 . The present results show potential overcoming challenges in ohmic contact formation for high-power and high-frequency AlGaN electron devices with high Al composition.