Comparative study of defect energetics in HfO2 and SiO2

TL;DR

This study uses ab initio density functional theory calculations to compare defect formation energetics in HfO2 and SiO2, revealing insights into defect stability and interface chemistry relevant for material applications.

Contribution

It provides the first detailed comparison of defect energetics in HfO2 and SiO2 using ab initio methods, highlighting defect formation preferences.

Findings

Si substitutional defects are most likely to form in HfO2 across various chemical potentials.

Oxygen vacancies are more energetically favorable in SiO2 than in HfO2.

Oxygen-deficient HfO2 can deplete oxygen from underlying SiO2.

Abstract

We perform ab initio calculations, based on density functional theory, of substitutional and vacancy defects in the monoclinic hafnium oxide (m-HfO2) and alpha-quartz (SiO2). The neutral oxygen vacancies and substitutional Si and Hf defects in HfO2 and SiO2, respectively, are investigated. Our calculations show that, for a large range of Hf chemical potential, Si substitutional defects are most likely to form in HfO2, leading to the formation of a silicate layer at the HfO2/Si interface. We also find that it is energetically more favorable to form oxygen vacancies in SiO2 than in HfO2, which implies that oxygen deficient HfO2 grown on top of SiO2 will consume oxygen from the SiO2.