Effect of anharmonicity on energy relaxation of a dissipative quantum oscillator

Kumar, Ramesh; Kumar, Pradeep

doi:10.1007/s12039-019-1599-4

Cited by 6 publications

(1 citation statement)

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“…Thermal energy generation is affected by the phonon scattering process and the relaxation time of excited charge carriers [4,5]. Time-dependent frequency shift and the evolution of the bandwidth in the excited state are correlated with anharmonicity [6]. It has been reported that multimode optical thermal sensors in the cryogenic temperature range are applied for thermometry using the concept of the frequency shift in the variation of the temperature due to the anharmonicity of the ZnTe [7].…”

Section: Introductionmentioning

confidence: 99%

Effect of phonon anharmonicity on thermal conductivity of ZnTe Thin films

Ghosh,

Ghorai,

Sahoo

2024

J. Phys.: Condens. Matter

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The ZnTe thin film is a potential material for optoelectronic devices in extreme temperature and radiation environments. In this report, the thermal conductivity of ZnTe films is measured non-invasively using the Micro-Raman method and correlated with the phonon anharmonic effect. The evolution of crystalline ZnTe thin films from Te/ZnO bilayer by thermal annealing at 4500C has been observed above the melting point of Te, which is confirmed from X-ray diffraction and high-resolution transmission electron microscopy. The ZnTe thin films illustrate three longitudinal phonon modes with higher harmonics of nLO (n=3) at room temperature. Temperature-dependent Raman spectra in the range of 93 - 303 K are used to analyze the phonon anharmonicity from Raman shift, FWHM, and Phonon lifetime of the thin films. The Balkanski model is used to fit the anharmonicity-induced phonon frequency shift of nLO modes as a function of temperature, taking into account three- and four-phonon interactions. The intensity ratio of the I2LO/I1LO and I3LO/I2LO provide information about the electron-phonon coupling strength, which is influenced by the anharmonic effect. The laser power-dependant Raman spectra are used to determine the thermal conductivity of the ZnTe films, which is found to be approximately 9.68 Wm-1 K-1, remains relatively constant for all nLO modes, indicating that multi-phonon scattering process. The correlation between thermal conductivity and phonon anharmonicity can pave the way for understanding the phonon scattering process in ZnTe thin films for high-performance optoelectronic device applications in harsh conditions.

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