Zero temperature coefficient of sound velocity in vitreous silicon oxynitride thin films

Nagakubo, Akira; Tsuboi, Seiya; Kabe, Yoshiro; Matsuda, Satoru; Koreeda, Akitoshi; Fujii, Yasuhiro; Ogi, Hirotsugu

doi:10.1063/1.5098354

Cited by 10 publications

(7 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the photothermal effect [15], the surface temperature change is proportional to the change in probe light reflectivity, from which we evaluated the thermal conductivity. The details of our optical system, the calculation of the acoustic-wave speed, and elasticity are shown elsewhere [20][21][22][23]. Just after the excitation, however, the reflectivity change is highly affected by the electron thermalization process, and we adopt a reference sample in this paper to compensate this effect.…”

Section: Methodsmentioning

confidence: 99%

Phonon propagation in isotopic diamond superlattices

et al. 2021

Self Cite

View full text Add to dashboard Cite

The out-of-plane thermal conductivity and elastic constant of epitaxial [100] 12 C/ 13 C superlattice diamonds with layer thicknesses of 1, 30, and 100 nm are evaluated by picosecond ultrasound spectroscopy. The measured elastic constants of the superlattices are equivalent to those of single-layer diamond thin films. This result confirms our success in synthesizing superlattice specimens with few defects at the interfaces. Therefore, the phonon transport behavior is governed by the mass difference, not the interfacial defects. The measured thermal conductivity of the superlattices is lower than that of a pure 12 C isotope diamond thin film. We estimated the lattice thermal conductivity using the lattice dynamics calculation, attributing the lowered thermal conductivity to the decrease in the phonon group velocity in superlattices. We further consider the effect of mini-umklapp scattering in the superlattice, which explains the dependence of the thermal conductivity on the layer thickness. We reveal that the mini-umklapp scattering effect becomes significant only for an isotope diamond superlattice because of the high Debye temperature and large relative mass difference.

show abstract

Section: Methodsmentioning

confidence: 99%

Phonon propagation in isotopic diamond superlattices

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…These values are determined by the reported experimental data on the phonon dispersion relationship 23 and the measured elasticity 22 via picosecond ultrasound spectroscopy. [24][25][26][27] The details of determining the bond stiffnesses, the lattice dynamics model, 22 and the experimental system [28][29][30] are shown elsewhere. The interatomic distance is calculated by the reported lattice constant.…”

Section: Theoretical Calculationmentioning

confidence: 99%

Lattice thermal conductivity in isotope diamond asymmetric superlattices

Weng,

Nagakubo,

Watanabe

et al. 2021

Preprint

View full text Add to dashboard Cite

We study lattice thermal conductivity of isotope diamond superlattices consisting of 12 C and 13 C diamond layers at various superlattice periods. It is found that the thermal conductivity of a superlattice is significantly deduced from that of pure diamond because of the reduction of the phonon group velocity near the folded Brillouin zone. The results show that asymmetric superlattices with different number of layers of 12 C and 13 C diamonds exhibit higher thermal conductivity than symmetric superlattices even with the same superlattice period, and we find that this can be explained by the trade-off between the effects of phonon specific heat and phonon group velocity. Furthermore, impurities and imperfect superlattice structures are also found to significantly reduce the thermal conductivity, suggesting that these effects can be exploited to control the thermal conductivity over a wide range.

show abstract

“…22,23) By depositing a ∼10 nm metallic film, picosecond ultrasonics can excite ultrasound in dielectric material through the thermal expansion of the metal. 24) For "thick" nm films (>400 nm), we have measured the longitudinal elastic constants and sound velocities of SiO 2 , 25,26) SiON, 27) and AlN 28) films by observing Brillouin oscillation. 29,30) Brillouin oscillation is caused by light interference between reflected light at the surface and diffracted light by the propagating acoustic pulse in the dielectric material, and its oscillation period corresponds to half of the wavelength of the probe light in the material.…”

Section: Introductionmentioning

confidence: 99%

Elastic constant of dielectric nano-thin films using three-layer resonance studied by picosecond ultrasonics

Fukuda

Nagakubo

Ogi

2021

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

Elastic constants and sound velocities of nm order thin films are essential for designing acoustic filters. However, it is difficult to measure them for dielectric thin films. In this study, we use a three-layer structure where a dielectric nano-thin film is sandwiched between thicker metallic films to measure the longitudinal elastic constant of the dielectric film. We propose an efficiency function to estimate the optimal thicknesses of the components. We use Pt/NiO/Pt three-layer films for confirming our proposed method. The determined elastic constant of NiO deposited at room temperature is smaller than the bulk value by ∼40%. However, it approaches the bulk value as the deposition temperature increases. We also reveal that the uncertainty of the elastic constant of the Pt film insignificantly affects the accuracy of the determined elastic constant of NiO in this structure.

show abstract

Zero temperature coefficient of sound velocity in vitreous silicon oxynitride thin films

Cited by 10 publications

References 40 publications

Phonon propagation in isotopic diamond superlattices

Phonon propagation in isotopic diamond superlattices

Lattice thermal conductivity in isotope diamond asymmetric superlattices

Elastic constant of dielectric nano-thin films using three-layer resonance studied by picosecond ultrasonics

Contact Info

Product

Resources

About