Surface optical phonon modes in hexagonal shaped Al0.97Ga0.03N nanostructures

Sivadasan, A. K.; Singha, Chirantan; Raghavendra, K.; Amirthapandian, S.; Bhattacharyya, Anirban; Dasgupta, Arup; Dhara, Sandip

doi:10.1007/s00339-017-1139-3

Cited by 11 publications

(6 citation statements)

References 26 publications

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Section: Introductionmentioning

confidence: 92%

“…It is well found that the SO phonon and others such as acoustic and second-order mode frequencies depend on size, surface defects, functional moieties, dielectric medium, and growth temperature of the nanostructures. ,, The intensity and position of other surface-related phonon frequencies including combination modes were also found to vary with size. − The intensity of an acoustic mode from CdSe NPs was reported to decrease with an increase in the particle size . Similarly, defect-induced interruption of the lattice periodicity at surfaces in NPs was found to alter the zone boundary phonons and consequently its position and intensity. ,, For instance, surface defects acted on the phonon modes of the Zn-embedded ZnO NPs …”

Section: Introductionmentioning

confidence: 96%

“…23,24 The vibration of surface atoms of the polar material, with a confined amplitude near the surface, decreases exponentially with depth and consequently allows the occurrence of the SO mode, also known as the Froḧlich mode. 2, 25,26 Normally, the SO mode is seen because of breaking of the translational symmetry of surface potential which activates a large wave vector. 27 the mode frequency is separate from the other Raman-active optical phonons.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, surface effects become prominent in nanomaterials as the size decreases and leads to spatial confinement of bulk phonon modes with varying amounts of phonon density states. − The corresponding frequency is found in between transverse optical (TO) and LO phonon modes at the Brillouin zone center (wave vector, q = 0). , The vibration of surface atoms of the polar material, with a confined amplitude near the surface, decreases exponentially with depth and consequently allows the occurrence of the SO mode, also known as the Fröhlich mode. ,, Normally, the SO mode is seen because of breaking of the translational symmetry of surface potential which activates a large wave vector . Thus, the mode frequency is separate from the other Raman-active optical phonons. ,, It is, therefore, a special and unique feature of nanostructures with surface perturbation over the bulk crystals .…”

Section: Introductionmentioning

confidence: 99%

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Invoking Obscured Surface Optical, Acoustic, and Anharmonic Phonon Modes and Their Modulation by Synthesis Conditions and Arrangement of the Surface in 0D ZnS

et al. 2020

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For low-dimensional systems, symmetry breaking and surface reconstruction are critical for the observation of special vibrational properties of technical significance such as surface optical (SO), anharmonic, and disorder-activated phonon (DAP) modes. First, earlier unobserved modes such as SO and DAP are disclosed for cubic zinc sulfide (ZnS) nanoparticles (NPs) of 3–5 nm size by adopting an experimental process without any stabilizing agent at low temperatures. The emphatic influence of surface defects, in particular, elemental “S” in the perturbation of phonon propagation, is elaborated. Furthermore, studies with surface functionalization and heat treatment provide significant insights into the critical influence of synthesis conditions that possibly withhold such surface modes in the cubic zero-dimensional ZnS in previous reports. The effect of crystal size is also elaborated. Moreover, the experimentally observed SO mode is verified theoretically for different ZnS NPs along with the effect of the dielectric medium. In addition to structural elucidation by high-resolution transmission electron microscopy, electron energy loss spectroscopy, Raman spectroscopy, and temperature-dependent photoluminescence measurements, they provide evidence of nanoscale surface modulation as a necessary condition to evolve such active surface modes in the cubic phase ZnS NPs.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Invoking Obscured Surface Optical, Acoustic, and Anharmonic Phonon Modes and Their Modulation by Synthesis Conditions and Arrangement of the Surface in 0D ZnS

et al. 2020

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“…To explain the frequency shift of the phonon mode at the nanocrystal edge, we analytically calculated the surface optical modes in the nanocrystal, approximating it as an AlN cylinder, following the work of ref. 51 , and the practical examples of this approach 20,54,55 .…”

Section: Nanoscale Advances Accepted Manuscriptmentioning

confidence: 99%

Local phonon imaging of AlN nanostructures with nanoscale spatial resolution

et al. 2023

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Dispersive Spectra of Fröhlich Phonon Modes in Wurtzite Nitride Nanoholes with Circular and Square Cross Sections

Zhang,

Wang,

Liu

et al. 2024

Physica Status Solidi (b)

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Semiconductor nanoholes have garnered significant interest due to their unique nanotopological structures, which can result in distinct physicochemical characteristics. This study delves into the properties of crystal vibrations in nanohole structures. The analytic Fröhlich phonon state and dispersion relationship in wurtzite nanoholes, with circular and square cross sections (CS), are derived using the macroscopic dielectric continuum model. It is found that two types of phonon modes, surface optical (SO) and half‐space (HS) modes, coexist in wurtzite nitride nanohole structures. These phonon modes and their dispersive behaviors in nanoholes significantly differ from those in nanowires due to the different nanotopological structures. Furthermore, the Fröhlich electron–phonon interaction Hamiltonians for SO and HS phonon modes in nanoholes are obtained based on a field quantization scheme. Numerical calculations on wurtzite AlN nanoholes reveal that the shape of the CS has a remarkable influence on the dispersive spectra of SO and HS phonon modes. Additionally, it is found that the dielectric medium significantly affects the dispersive features of SO modes, while its influence on the dispersive behavior of HS modes is negligible. The profound physical mechanisms behind these observations are deeply analyzed.

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Surface optical phonon modes in hexagonal shaped Al0.97Ga0.03N nanostructures

Cited by 11 publications

References 26 publications

Invoking Obscured Surface Optical, Acoustic, and Anharmonic Phonon Modes and Their Modulation by Synthesis Conditions and Arrangement of the Surface in 0D ZnS

Invoking Obscured Surface Optical, Acoustic, and Anharmonic Phonon Modes and Their Modulation by Synthesis Conditions and Arrangement of the Surface in 0D ZnS

Local phonon imaging of AlN nanostructures with nanoscale spatial resolution

Dispersive Spectra of Fröhlich Phonon Modes in Wurtzite Nitride Nanoholes with Circular and Square Cross Sections

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