Raman scattering from boron nitride coatings at high temperatures

Schaaf, Joel W.

doi:10.1063/1.348695

Cited by 41 publications

(33 citation statements)

References 16 publications

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“…Figure 6 shows the intrinsic FWHM of the E high 2g mode as a function of temperature determined from the Raman measurements. The rate of FWHM increase with temperature is similar to that reported for a polycrystalline pyrolytic coating [23], but the values of FWHM are consistently ∼1.5 cm −1 below those of Ref. [23], which can be ascribed to the higher crystalline quality of our monocrystalline sample.…”

Section: Line Broadening and Phonon Decay Channelssupporting

confidence: 84%

“…Whereas phonon anharmonicities have been studied in detail by means of Raman scattering experiments in the closely related graphite and graphene structures [21,22], no information exists in the literature about phonon anharmonic decay in h-BN. The temperature dependence of the Raman frequency and linewidth of the E high 2g mode was reported for temperatures above RT for a polycrystalline BN coating, and it was concluded that it could not be explained in terms of a simple model involving a single phonon decay channel [23]. Strong coupling of optical phonons to electrons in graphite yields ultrafast electron relaxation via excitation of a hot phonon population, whose lifetime was estimated to be of 7 ps [24].…”

Section: Introductionmentioning

confidence: 99%

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Temperature dependence of Raman-active phonons and anharmonic interactions in layered hexagonal BN

et al. 2016

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We present a Raman scattering study of optical phonons in hexagonal BN for temperatures ranging from 80 to 600 K. The experiments were performed on high-quality, single-crystalline hexagonal BN platelets. The observed temperature dependence of the frequencies and linewidths of both Raman active E 2g optical phonons is analyzed in the framework of anharmonic decay theory, and possible decay channels are discussed in the light of density-functional theory calculations. With increasing temperature, the E high 2g mode displays strong anharmonic interactions, with a linewidth increase that indicates an important contribution of four-phonon processes and a marked frequency downshift that can be attributed to a substantial effect of the four-phonon scattering processes (quartic anharmonicity). In contrast, the E low 2g mode displays a very narrow linewidth and weak anharmonic interactions, with a frequency downshift that is primarily accounted for by the thermal expansion of the interlayer spacing.

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Section: Line Broadening and Phonon Decay Channelssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Temperature dependence of Raman-active phonons and anharmonic interactions in layered hexagonal BN

et al. 2016

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“…As a result, thin-film aging effects are mainly caused by absorption of water molecules due to the thin-film microporosity followed by a BN hydrolysis as was pointed out by Hubácek and Ueki. 8 Infrared ͑IR͒ 4,[9][10][11][12][13][14] and Raman spectroscopy, [15][16][17][18][19][20] as well as IR and visible-light ͑VIS͒ spectroscopic ellipsometry ͑SE͒ [21][22][23][24][25] were used to investigate BN thin-film optical and structural properties. It was demonstrated that polarized IR reflection ͑PIRR͒ measurements, 26,27 IR-SE [28][29][30][31][32][33][34] and VIS-SE 25,30 are useful techniques to resolve the BN microstructure from the thin-film optical properties.…”

Section: Introductionmentioning

confidence: 99%

In situ infrared and visible-light ellipsometric investigations of boron nitride thin films at elevated temperatures

Franke

Schubert

Hecht

et al. 1998

Journal of Applied Physics

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In situ infrared ͑IR͒ spectroscopy and visible-light ͑VIS͒ spectroscopic ellipsometry over the spectral range from 700 to 2000 cm Ϫ1 and 1.5-3.5 eV, respectively, were used to investigate the optical behavior of boron nitride ͑BN͒ thin films at temperatures from room temperature ͑RT͒ to 600°C. The polycrystalline hexagonal ͑h͒ and mixed-phase h-and cubic (c)-BN thin films were deposited by magnetron sputtering on ͓001͔ silicon. We observe a reversible moisture incorporation process in as-grown h-BN samples. When stored in normal ambient, the h-BN thin films absorb water into thin-film micropores. When annealed in ultrahigh vacuum or a dry nitrogen atmosphere, the samples expel moisture but retain their microstructure. This is observable by reduction of the thin-film refractive indices in accordance with changes in the IR lattice resonance behavior. The optical properties of high c-BN content thin films remain unchanged during annealing. And both intrinsic h-and c-BN thin-film VIS refractive indices are nearly temperature independent, at least up to 600°C. Therefore, RT BN optical constants can be used for feedback loop control in in situ thin-film growth at temperatures up to 600°C. ͓S0021-8979͑98͒07613-0͔

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“…The acoustic modes have symmetry E 1u A 2u and the crystal field gives rise to a splitting between longitudinal (LO) and transverse optical phonons for the other E 1u modes, whereas the E 2g modes remain doubly degenerate each. In Table I we compare our calculations with the experimental data reported for the ÿ point by Raman [14,[21][22][23][24] and infrared [22,25] spectroscopy. The agreement between both data sets is excellent, the largest difference being a 5% underestimate of the A 2u mode, similar to that reported by previous ab initio calculations [12,13].…”

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confidence: 99%

Vibrational Properties of Hexagonal Boron Nitride: Inelastic X-Ray Scattering andAb InitioCalculations

et al. 2007

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The phonon dispersion relations of bulk hexagonal boron nitride have been determined from inelastic x-ray scattering measurements and analyzed by ab initio calculations. Experimental data and calculations show an outstanding agreement and reconcile the controversies raised by recent experimental data obtained by electron-energy loss spectroscopy and second-order Raman scattering. DOI: 10.1103/PhysRevLett.98.095503 PACS numbers: 63.20.Dj, 61.10.Eq, 63.10.+a, 71.15.Mb Besides their intermediate structure between twodimensional sheets and 3D crystals, layered compounds are relevant materials for storage of other compounds [1] and as potential building blocks for nanotubes [2]. Among these materials, graphite and hexagonal boron nitride (h-BN) have drawn most of the attention due to their simple hexagonal structure, their fascinating properties, and the successful realization of carbon-[3] and more recently BN [4 -6] nanotubes. A wide band gap semiconductor, h-BN, has been grown successfully very recently as a single crystal. It exhibits a lasing behavior at 5.8 eV that makes it attractive for optoelectronic applications in the ultraviolet energy range [7].Despite the tremendous effort devoted to the characterization of physical properties of h-BN, the lattice dynamics, responsible for the elastic and thermodynamic properties such as the heat capacity and the thermal expansion, are still under debate. First principles calculations are generally accepted as the most accurate theoretical description of the lattice dynamics [8]. Recently, for h-BN, the validity of state of the art ab initio calculations was put in doubt by two experiments: Rokuta et al. [9] reported the only experimental data available for the phonon dispersion relations by electron-energy loss spectroscopy (EELS) performed on a monolayer of h-BN deposited on a Ni(111) substrate. Among several deviations from ab initio calculations of the lattice dynamics both for a monolayer [10,11] and for bulk h-BN [12,13], the EELS data show a degeneracy at the K point between acoustic (ZA) and optical (ZO) modes polarized along the c axis. The origin of this degeneracy has not been clarified yet. More recently [14], second-order Raman spectra of single crystalline h-BN revealed two features that contested the predictions based on a simple doubling of the energy scale of ab initio calculations for the one-phonon density of states, suggesting deviations up to 40% for the calculated energy of the TA branch in the K-M region. Since h-BN is a relevant material for UV lasing, it is imperative to resolve the existing controversies and critically assess the quality of the ab initio calculations. Furthermore, we need exact information on the lattice dynamics in order to properly understand the contributions due to electron-phonon coupling observed in the cathodoluminescence and absorption spectra of h-BN [7] and BN nanotubes [15,16].In this Letter we address the above discrepancies in the vibrational properties by reporting inelastic x-ray scattering (IXS) measurements...

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Raman scattering from boron nitride coatings at high temperatures

Cited by 41 publications

References 16 publications

Temperature dependence of Raman-active phonons and anharmonic interactions in layered hexagonal BN

Temperature dependence of Raman-active phonons and anharmonic interactions in layered hexagonal BN

In situ infrared and visible-light ellipsometric investigations of boron nitride thin films at elevated temperatures

Vibrational Properties of Hexagonal Boron Nitride: Inelastic X-Ray Scattering andAb InitioCalculations

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