Influence of Assist Ion Bombardment on Mechanical Loss of Amorphous Tantala Thin Films for Gravitational Wave Interferometers

ORAL

Abstract

Thermal noise in high-reflectivity coatings is critical for improving the sensitivity of future gravitational wave detectors. Amorphous tantala (Ta2O5) thin film, used as high-index material, with lower mechanical loss is expected as one solution to further reduce the coating thermal noise. The material is also regarded as promising candidate for use in resistance random access memory as well as optical applications. In this work, amorphous tantala thin films have been deposited by reactive ion beam sputtering with assist Ar+ and Xe+ ion bombardment to investigate the effect of ion-induced surface diffusion on coating's mechanical and structural properties. The results show that the atomic structure of ion bombarded tantala thin films remain amorphous and their composition is mostly stoichiometric. The mechanical loss of ion-bombarded tantala coatings shows no significant improvement compared to non-bombarded samples. The coating loss angle of tantala is insensitive to ion dose or ion mass. An analysis based on surface diffusivity suggests that the ion-assisted surface diffusivity may be insignificantly modified under the current typical deposition conditions.

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Presenters

  • Le Yang

    Colorado State Univ

Authors

  • Le Yang

    Colorado State Univ

  • Emmett Randel

    Colorado State Univ

  • Gabriele Vajente

    California Institute of Technology, LIGO Lab, California Institute of Technology

  • Alena Ananyeva

    LIGO Laboratory, California Institute of Technology, Pasadena, CA, USA, California Institute of Technology, LIGO Laboratory, California Institute of Technology

  • Eric Keith Gustafson

    LIGO Laboratory, California Institute of Technology, Pasadena, CA, USA, California Institute of Technology, LIGO Laboratory, California Institute of Technology, LIGO Lab, California Institute of Technology

  • Ashot Markosyan

    Department of Applied Physics, Ginzton Laboratory, Stanford University, Stanford, CA, USA, Stanford University, Edward L. Ginzton Laboratory, Stanford University

  • Martin Fejer

    Department of Applied Physics, Ginzton Laboratory, Stanford University, Stanford, CA, USA, Stanford University, Applied Physics, Stanford University, E. L. Ginzton Laboratory, Stanford University, Ginzton Laboratory, Stanford University, E. L. Ginzton Laboratory, Stanford

  • Carmen Susana Menoni

    Colorado State Univ, Department of Electrical and Computer Engineering and NSF ERC for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, CO, USA, Department of Electrical and Computer Engineering, Colorado State University