GWADW2023 - Gravitational-Wave Advanced Detector Workshop

Mechanical and Optical Characterization of sputtered amorphois GaN thin film for high reflectivity and low-loss coatings

23 May 2023, 18:00

1h 30m

Hotel Hermitage, La Biodola, Isola d'Elba

Poster Coating thermal noise Tuesday Poster session

Speaker

Diana Lumaca (Università di Roma Tor Vergata e INFN Sezione di Roma Tor Vergata)

Description

In present gravitational wave (GW) detectors, the limiting noise at mid-frequency range is due to the Brownian thermal noise in the multilayer reflective coating, in particular the intrinsic dissipation of the high refractive index material. The anelastic behavior of amorphous materials is explained by the presence of metastable states that are separated by an energy barrier. 

To reduce the dissipation in the material a reduction of the total density of metastable state is needed. Amorphous films whose constitutive atoms have a coordination number larger than 3 should be characterized by a low amount of these states. Indeed, the structure is more rigid making structural reorganization more difficult.

Sputtered amorphous GaN has been considered as a possible candidate for the high refractive index material for future GW detector mirrors. After a first optimization of the deposition parameters, an explorative investigation on mechanical and optical properties has been conducted through GeNS and ellipsometry measurements.

Presentation materials

Poster_versione6-2.pdf