The role of oxygen-related defects and hydrogen impurities in HfO2 and ZrO2

We investigate the properties of oxygen-related defects and hydrogen impurities in monoclinic HfO2 and ZrO2 using first-principles calculations based on a hybrid functional. We examine how the formation energy of these defects depend on the Fermi level and the chemical potential. By aligning the valence-and conduction-band edges of these oxides to those of Si, we evaluate the possibility of these defects acting as carrier traps or sources of fixed charge in Si/HfO2 and Si/ZrO2. While the oxygen vacancy (V-O) appears more likely to act as a carrier trap, we find oxygen and hydrogen interstitials (O-i and H-i) as well as substitutional hydrogen (H-O) to have much lower formation energies for relevant Fermi levels and chemical potentials. (C) 2011 Elsevier B.V. All rights reserved.