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 O3-Al2O3/HfO2 (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·cm2 was obtained. High gate leakage associated with the HfO2 high-k gate dielectric was effectively blocked by the 5-nm O3-Al2O3 insertion layer grown by atomic layer deposition, contributing to a high I ON/I OFF ratio of 6 × 106 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.