Spectroscopic properties of oxygen vacancies in ${\text{LaAlO}}_3$

Journal Article · Fri Apr 01 00:00:00 EDT 2016 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.93.134114· OSTI ID:1253836

Dicks, Oliver A.; Shluger, Alexander L.; Sushko, Peter V.; Littlewood, Peter B.

Oxygen vacancies in LaAlO3 (LAO) play an important role in the formation of the 2-dimensional electron gas observed at the LaAlO3/SrTiO3 interface and affect the performance of MOSFETs using LAO as a gate dielectric. However, their spectroscopic properties are still poorly understood, which hampers their experimental identification. Here we predict the absorption spectra and ESR parameters of oxygen vacancies in LAO using periodic and embedded cluster models and Density Functional Theory (DFT). The structure, charge distribution, and spectroscopic properties of the neutral (V0O) and charged (V+O and V2+O ) oxygen vacancies in cubic and rhombohedral LaAlO3 are investigated. The highest intensity optical transitions (calculated using time dependent DFT (TDDFT)), from the oxygen vacancy states to the conduction band states have onsets at 3.5 and 4.2 eV for V0O and 3.6 eV for V+O in rhombohedral LAO and 3.3 and 4.0 eV for V 0O and 3.4 eV for V+O in cubic LAO, respectively. Also reported are the isotropic g-value (2.004026) and hyperfine coupling constants of V+O which are compared to the experimental data obtained using electron spin resonance (ESR) spectroscopy, and accurately predict both the position and the width (3 mT) of its ESR signature. These results may further facilitate the experimental identification of oxygen vacancies in LAO and help to establish their role at the LAO/STO interfaces and in nanodevices using LAO.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1253836
• Report Number(s): PNNL-SA-116034
• Journal Information: Physical Review B, Vol. 93, Issue 13; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English