High-performance enhancement-mode GaN-based p-FETs fabricated with O3-Al2O3/HfO2-stacked gate dielectric

Abstract In this letter, an enhancement-mode (E-mode) GaN p-channel field-effect transistor (p-FET) with a high current density of −4.9 mA/mm based on a O 3 -Al 2 O 3 /HfO 2 (5/15 nm) stacked gate dielectric was demonstrated on a p ++ -GaN/p-GaN/AlN/AlGaN/AlN/GaN/Si heterostructure. Attributed to the p ++ -GaN capping layer, a good linear ohmic I − V characteristic featuring a low-contact resistivity ( ρ c ) of 1.34 × 10 −4 Ω·cm 2 was obtained. High gate leakage associated with the HfO 2 high- k gate dielectric was effectively blocked by the 5-nm O 3 -Al 2 O 3 insertion layer grown by atomic layer deposition, contributing to a high I ON / I OFF ratio of 6 × 10 6 and a remarkably reduced subthreshold swing (SS) in the fabricated p-FETs. The proposed structure is compelling for energy-efficient GaN complementary logic (CL) circuits.