Physical properties and band structure of reactive molecular beam epitaxy grown oxygen engineered HfO2±x

We have conducted a detailed thin film growth structure of oxygen engineered monoclinic HfO2±x grown by reactive molecular beam epitaxy. The oxidation conditions induce a switching between (1¯11) and (002) texture of hafnium oxide. The band gap of oxygen deficient hafnia decreases with increasing amount of oxygen vacancies by more than 1 eV. For high oxygen vacancy concentrations, defect bands form inside the band gap that induce optical transitions and p-type conductivity. The resistivity changes by several orders of magnitude as a function of oxidation conditions. Oxygen vacancies do not give rise to ferromagnetic behavior.