Evidence for the existence of guided longitudinal acoustic phonons in ZnSe films on GaAs

Hillebrands, B.; Lee, S.; Stegeman, George I.; Cheng, Hai‐Ping; Potts, J. E.; Nizzoli, F.

doi:10.1103/physrevlett.60.832

Cited by 78 publications

(33 citation statements)

References 9 publications

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“…The calculated velocity is very close to the longitudinal sound velocity of ZnSe film. As previously found in the ZnSe/GaAs by Hillebrands et al, 3 this mode should be the longitudinal counterpart to the Rayleigh wave, i.e., the longitudinal guided mode ͑LGM͒, with a phase velocity slightly below the longitudinal sound velocity. The so-called LGM is also observed as an inner ring in Fig.…”

Section: A Vibrational Spectra In Transparent Filmssupporting

confidence: 68%

“…[2][3][4][5][6][7][8] In a conventional Brillouin spectroscopy ͑CBS͒ system, the observation of the acoustic excitations involves scanning a FP and using a photomultiplier tube ͑PMT͒ to record the phonon spectrum. 9,10 Only on-axis light is allowed to contribute to the signal, and only a fraction of the inelastically scattered light is collected, making the CBS inefficient.…”

Section: Introductionmentioning

confidence: 99%

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Vibrational excitations in thin films studied by spatial dispersion Brillouin spectroscopy

et al. 1996

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By combining a tandem multipass Fabry-Pérot ͑FP͒ interferometer with a charge-coupled-device ͑CCD͒ imaging detector, we have successfully observed surface Rayleigh waves, longitudinal guided modes, and bulk acoustic modes in dilute magnetic semiconductors, Si-and Ge-based films and superlattices. The inelastically scattered light from acoustic modes is transmitted through the FP off-axis, and is focused on the CCD where it forms concentric rings. We also have demonstrated that the high sensitivity of our system allows the observation of weak bulk acoustic modes from opaque a-Si:H/a-SiN x :H superlattices.

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Section: A Vibrational Spectra In Transparent Filmssupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Vibrational excitations in thin films studied by spatial dispersion Brillouin spectroscopy

et al. 1996

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“…LGM's in one adsorbed layer [14][15][16][17] were investigated by Brillouin light scattering, and the experimental results were found to be in agreement with a Brillouin scattering cross-section theory. 16 Some very recent papers 19,20 gave experimental evidence and theoretical explanation of Brillouin light scattering from sagittal surface acoustic phonons in a structure composed of a Si-SiO 2 double layer on a Si substrate.…”

Section: Introductionmentioning

confidence: 59%

“…Some years ago, [13][14][15][16][17][18][19][20][21] much attention has been devoted to the propagation of acoustic modes lying above the substrate velocity of sound and at the vicinity of the longitudinal threshold of the adsorbate, the so-called longitudinal guided modes ͑LGM's͒. The LGM's are resonances ͑also called leaky or pseudowaves͒ with a displacement field having longitudinal character and propagating in the film.…”

Section: Introductionmentioning

confidence: 99%

Resonant guided elastic waves in an adsorbed bilayer: Theoretical analysis of the density of states

1997

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We study resonant acoustic waves of sagittal polarization in a bilayer deposited on a substrate. Such resonances were initially studied by Brillouin light scattering in a buffer silica layer of a Si-SiO 2 bilayer on a Si substrate. Using a Green's-function method, we have obtained the local and total densities of states as a function of the frequency and the wave vector k ʈ parallel to the interfaces. When the velocities of sound in the buffer layer are higher than those in the topmost layer the former acts as a barrier between phonons of the topmost layer and those of the substrate; therefore well-confined resonant waves may exist in the higher slab, which appear as well-defined peaks in the density of states. The positions of these peaks enable us to study the speed of resonant modes as a function of the parallel wave vector and the thicknesses of the buffer and topmost layers. Specific applications of our analytical results are given in this paper for a GaAs-Si bilayer on a GaAs substrate.

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“…3,4 At a higher velocity range between the longitudinal sound velocities of the film (V F L ) and substrate (V S L ), the longitudinal guided mode ͑LGM͒ exists when V F L ϽV S L , and is characterized by mode displacements primarily along the film plane and a phase velocity close to V F L . 5 Excitations lying within these two distinct transverse or longitudinal velocity bands provide for a complete description of acoustic waves in a soft film on a hard material ͑i.e., V F T ϽV S T ͒, and have been extensively studied. [6][7][8][9][10] In the opposite limit, i.e., for hard films deposited on soft substrates (V S T ϽV F T ), only one surface acoustic wave ͑SAW͒, identified as the Rayleigh wave, exists in a narrow velocity range limited by V S T , provided the film thickness ͑h͒ is below a critical value.…”

mentioning

confidence: 99%

Observation of guided longitudinal acoustic modes in hard supported layers

et al. 1999

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We report experimental as well as theoretical evidence for the occurrence of a high-frequency acoustic excitation, identified as a longitudinal guided mode, in elastically hard films supported on a soft substrate. While existence criteria related to the transverse and longitudinal sound velocities in the film and substrate argue for strong decay channels into the substrate, the excitation is evident as a clear peak in the Brillouin light scattering spectra. A Green's function formalism accounts for the existence of this excitation and provides insight into its properties as illustrated for diamond-like-carbon layers deposited on silicon.

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Evidence for the existence of guided longitudinal acoustic phonons in ZnSe films on GaAs

Cited by 78 publications

References 9 publications

Vibrational excitations in thin films studied by spatial dispersion Brillouin spectroscopy

Vibrational excitations in thin films studied by spatial dispersion Brillouin spectroscopy

Resonant guided elastic waves in an adsorbed bilayer: Theoretical analysis of the density of states

Observation of guided longitudinal acoustic modes in hard supported layers

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