First principles investigation of charge transition levels in monoclinic, orthorhombic, tetragonal, and cubic crystallographic phases of HfO2

Abstract

A first-principles study of native point defects in monoclinic, cubic, two different tetragonal, and five different orthorhombic phases of hafnia (HfO2) is presented. They include vacancy of tri-coordinated and tetra-coordinated oxygen, metal vacancy, interstitial metal, and interstitial oxygen. Defect formation energy, trap depth, and relaxation energy upon optical excitation of defects are listed. The trap depth of oxygen vacancies shows little variation among different phases compared to other defects. Results of the trap depth are compared against measurements and found to have reasonable agreement.