Light-scattering observation of surface acoustic modes in high-order Brillouin zones of a Si(001) grating

Abstract

In Brillouin light-scattering (BLS) measurements of an ion-milled Si(001) surface grating with grating wavelength AG =0.35 pm, we have observed numerous high-order zone-folded surface acoustic modes between the second and third zone boundaries associated with the grating. A surprisingly intense signal from a zone-folded longitudinal resonance was observed in the absence of direct hybridization with the Rayleigh modes. The relative intensities of all of the modes have been calculated by allowing for coupling between modes related by up to two grating reciprocal-lattice vectors, and for a grating profile with nonzero first and second Fourier amplitudes. The Fourier amplitudes inferred from the BLS measurements and calculations agree very well with those obtained from a direct measurement of the grating profile using atomic-force microscopy. Recently, Brillouin light-scattering (BLS) measure

Acoustic vibrations in free‐standing single‐, bi‐layer nanomembranes and patterned wires

“…7b, when the width of the wire is close to the separation (D ∼ W = 320 nm). Folding of the Rayleigh type modes has been previously reported in grating-like surfaces supported on a semi-infinite substrate [48,49]. The folding effects we observe however differ from these previous reports in that our observations relate to wires on freely suspended membranes and thus enable the effects of the wires on the flexural and dilational modes belonging to the hard SiN membrane be investigated.…”

Finite element analysis of true and pseudo surface acoustic waves in one-dimensional phononic crystals

“…Nevertheless, as was shown, e.g., for Si and LiNbO 3 , a periodically corrugated surface can support the propagation of LLSAWs. 14,43,44…”

“…[9][10][11][12] The artificial second-order periodicity, introduced by an array of grooves or metallic stripes, was shown to result in the appearance of surface Brillouin zones, zone folding, pseudo-SAWs, and in particular cases frequency band gaps. [12][13][14][15][16][17][18][19][20] The research from the last twenty years has pointed out numerous attractive properties of PnCs over wide length and frequency scales, which can be applied to, e.g., seismic waves filters, coherent phonon sources, tunable acoustic filters, waveguides, and thermal management. [21][22][23][24] RSWs can be described as non-dispersive SAWs propagating near the free surface of a homogenous solid state medium with a finite penetration depth into bulk.…”

Phononic dispersion of a two-dimensional chessboard-patterned bicomponent array on a substrate

“…[4][5][6][7] The few experimental studies that measured surface acoustic waves (SAWs) dispersion curves were based on one-dimensional (1D) structures. 3, [11][12][13] Among them are the determination of the SAW dispersion for a grating etched on a Si(001) wafer by Dutcher et al, 11 and the measurement of the phononic dispersions of 1D periodic arrays of stripes of two alternating materials by Zhang et al 3 It is of interest to investigate higher-dimensional periodic structures whose surface phononic dispersions are more complex and richer in features than those of the 1D phononic crystals.…”

“…Measurement of the frequency band structure of the acoustic waves was performed using Brillouin light scattering, a powerful tool for probing these waves in nanostructured materials. [3][4][5][6][7]11,12,14 Brillouin spectra were recorded in the 180 -backscattering geometry with the scattering plane normal to the sample's metal surface and with the phonon wavevector q along either the C-M or C-X directions. The k ¼ 514.5 nm radiation of an argon-ion laser was used to excite the p-p and p-s polarization spectra, with the scattered light frequency analyzed with a (3 þ 3)-pass tandem Fabry-Pérot interferometer a)…”