Silicon Nitride Stress Liner Impacts on the Electrical Characteristics of AlGaN/GaN HEMTs

TL;DR

This study investigates how silicon nitride stress liners influence the electrical properties of AlGaN/GaN HEMTs, revealing that while surface passivation dominates device performance, induced stress can effectively modify threshold voltage for normally-off operation.

Contribution

It demonstrates the impact of SiNx stress liners on threshold voltage tuning in AlGaN/GaN HEMTs through strain engineering.

Findings

Surface passivation dominates device performance.

Induced stress increases threshold voltage.

Strain engineering enables normally-off HEMTs.

Abstract

Due to the piezoelectric nature of GaN, the 2DEG in AlGaN/GaN HEMT could be engineered by strain. In this work, SiNx deposited using dual-frequency PECVD was used as a stressor. The output performance of the devices was dominated by the surface passivation instead of the stress effect. However, the threshold voltage was increased by the induced stress, supporting strain engineering as an effective approach to pursue the normally-off operation of AlGaN/GaN HEMTs.