Oxygen vacancies at the Si(001)/SiO₂ interface

High-k oxides deposited on silicon substrates form interfacial silicon dioxide layers. The interface layer is of importance in microelectronics, due both to charge transport at the silicon/silicon dioxide interface and to the oxide layer influencing the equivalent oxide thickness (EOT). Electrical characterization of low temperature thermal oxides grown by atomic layer deposition of hafnia dioxide indicates a dielectric constant at the interfacial region larger than for stochiometric SiO:. A proposed mechanism for the observed increase is the interface becomes oxygen deficient during the growth process. Oxygen vacancies in SiO₂ are examined by ab initio computations and are found to be more stable in the vicinity of the interface, thus identifying a chemical driving force for oxygen reduction at the interface. Copyright The Electrochemical Society.