High frequency organ-pipe modes in amorphous boron carbide observed using surface Brillouin scattering

Abstract

Amorphous boron carbide films of 2 micron thickness were deposited at room temperature by a thermal deposition process on single-crystal silicon substrates. The elastic constants of an amorphous B4C film have been successfully measured by surface Brillouin scattering as a function of temperature, in the process, revealing a phase transition at about 350°C. Quantized wave-vector components perpendicular to the film surface associated with organ-pipe modes occurring within the film were used in conjunction with elastodynamic Green's function calculations as well as independent measurement of longitudinal frequency from bulk excitations to extract the elastic constants. © 2007 IOP Publishing Ltd.