Letters 87, 183505 (2005) and may be found at http://dx.doi.org/10.1063/1.2119425Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

The energy levels of interstitial hydrogen in various wide band gap oxides are calculated using a density function based method that does not need a band gap correction. The positive charge state has a large stabilization energy due to the formation of an O–H bond. The hydrogen level is found to be shallow in CdO, ZrO2, HfO2, La2O3, LaAlO3, SnO2, TiO2, SrTiO3, PbTiO3, and SrBi2Ta2O9, but deep in MgO, Al2O3, SiO2, ZrSiO4, HfSiO4, and SrZrO3. It is borderline in SrO. The predictions are found to agree well with the experimental behavior of muonium in these oxides.

No abstract

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Nitrogen is known to reduce leakage currents and charge trapping in high-dielectric-constant gate oxides such as HfO 2 . We show that this occurs because nitrogen, substituting for oxygen atoms next to oxygen vacancy sites, repels the occupied gap states due to the neutral and positively charged oxygen vacancies out of the band gap into its conduction band. The state of the negatively charge vacancy is also repelled upwards but remains as a shallow gap state. This occurs because the vacancy becomes effectively positively charged; the adjacent Hf ions relax outwards from the vacancy and shift its states upwards. We show this using ab initio calculation methods which do not require an empirical correction to the band gap.

A theoretical study of the structural and electronic properties of GaAs:HfO2 interface is performed using the density functional theory method. For the interfaces with Ga−O bonds (formed between Ga-terminated GaAs surface and O-terminated HfO2 surface), we found that the interfaces with 10% and 20% interfacial oxygen removed are thermodynamically stable over a wide range of O chemical potential. By gradually decreasing the interfacial O content from 100% to 30% (by changing O chemical potential corresponding to varying the growth condition), the valence band offset increases from 1.06 to 3.34 eV. The analysis of the electronic structures indicates that for interfaces with high interfacial oxygen content, the interface gap states are induced by interfacial Ga dangling bonds and As−As dimer pairs, which are formed by interface atomic structure reconstruction. The decreasing interfacial oxygen content causes the decrease of the charge states of interfacial Hf and Ga leading to metallic interface states. For interfaces with low interfacial oxygen content, we found that As−As, Ga−Ga dimer pairs, and Ga and As dangling bonds are also formed and contribute to the interface gap states.