Surface Brillouin scattering in Titanium Carbide films

• Published in: Wave motion Vol. 68; pp. 78 - 87
• Main Authors: Sumanya, C., Comins, J.D., Every, A.G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-01-2017; Elsevier BV
• Subjects: Acoustic propagation; Brillouin zones; Elastic properties; Elastic waves; Elastodynamics; Film thickness; Green's functions; Phonons; Scattering; Simulation; Stiffening; Studies; Substrates; Surface acoustic waves; Surface Brillouin scattering; Thin films; Titanium carbide; Velocity; Wave propagation; Films; Surface Brillouin scattering; Elastic waves
• ISSN: 0165-2125; 1878-433X
• DOI: 10.1016/j.wavemoti.2016.08.011

Simulations of surface Brillouin scattering (SBS) spectra of TiC hard films on several substrates have been carried out over a range of film thickness from 5 nm to 1000 nm. The simulations are based on the elastodynamic Green’s function method that predicts the surface displacement amplitudes of acoustic phonons. These simulations provide information essential to understand and analyse experimental data emerging from SBS experiments. A thorough discussion of all possible surface acoustic waves propagating in a TiC film deposited on a substrate is presented. There are striking differences in the simulated SBS spectra depending on the respective elastic properties of the film and the substrate. One can either have stiffening or loading system. This can further be categorised into strong and weak stiffening or loading systems. For the first time the weak stiffening system is presented. The velocity dispersion of the modes as a function of the product of surface wavevector and thickness (q∥d) has also been simulated, which allows the elastic constants of the films to be determined.
•Thin supported films are categorised into four scenarios using TiC as an example.•Scenarios of both weak and strong stiffening and loading systems are simulated.•Excitations from these systems can be observed by surface Brillouin scattering.•These include Rayleigh, Sezawa, pseudo-Sezawa, Love and Stoneley waves.•These waves can be used in determination of elastic moduli of the films.