Plasma enhanced atomic layer deposition of HfO2—A potential gate dielectric for GaN-based devices

GaN-based devices are increasingly recognized as key components for next-generation power electronics. This leads to a strive toward achieving gate dielectrics on GaN with optimal electronic properties. In this article, we report the development of HfO2 thin films on GaN substrates using plasma enhanced atomic layer deposition (PEALD) technique. The atomic scale precision offered by ALD enabled the growth of high-quality HfO2 films. Atomic force microscopy reveals smooth surface morphology, while x-ray reflectometry confirms the formation of dense layers. When applied as a gate dielectric in GaN-based metal–oxide–semiconductor (MOS) capacitors, ∼25 nm HfO2 layers exhibit a high dielectric constant of ≈16, high breakdown field strength of ≈6.8 MV/cm, and low leakage current of ≈10−6 A/cm2, indicating their suitability for advanced applications. Our work provides a comprehensive study on the development and integration of PEALD HfO2 layers in GaN-based MOS devices.