Abstract
Abstract
In this work, we systematically studied the stoichiometry and thickness effects of low-pressure chemical vapor deposited SiN
x
bilayer stacks on the electrical properties of AlGaN/GaN heterojunction-based metal–insulator-semiconductor high electron mobility transistors. A Si-rich SiN
x
single layer reduces threshold voltage shift and hysteresis under gate stress but gives rise to high gate leakage. A near-stoichiometric SiN
x
single layer suppresses gate leakage but causes poor gate stability. A bilayer SiN
x
stack with an optimized thickness ratio improves both the gate stability and on-resistance while maintaining a low current leakage. The bilayer SiN
x
stack consisting of a 5 nm Si-rich SiN
x
interfacial layer and a 15 nm SiN
x
capping layer resulted in the lowest sheet resistance and the highest gate stability. Such enhanced gate stability is explained by the low density of trap states and the weakened electric field at the Si-rich SiN
x
/GaN interface and an extra positive charge at the bilayer interface.
Funder
National Natural Science Foundation of China
Guangdong Academy of Sciences
Key-Area Research and Development Program of Guangdong Province
Subject
Materials Chemistry,Electrical and Electronic Engineering,Condensed Matter Physics,Electronic, Optical and Magnetic Materials