1 0 0 0 OA Thermal conductivity of GeTe/Sb2Te3 superlattices measured by coherent phonon spectroscopy
- 著者
- Hase Muneaki Tominaga Junji
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.99, no.3, pp.031902, 2011
- 被引用文献数
- 11 6
We report on evaluation of lattice thermal conductivity of GeTe/Sb2Te3 superlattice (SL) by using femtosecond coherent phonon spectroscopy at various lattice temperatures. The time-resolved transient reflectivity obtained in amorphous and crystalline GeTe/Sb2Te3 SL films exhibits the coherent A1 optical modes at terahertz (THz) frequencies with picoseconds dephasing time. Based on the Debye theory, we calculate the lattice thermal conductivity, including scattering by grain boundary and point defect, umklapp process, and phonon resonant scattering. The results indicate that the thermal conductivity in amorphous SL is less temperature dependent, being attributed to dominant phonon-defect scattering.
- 著者
- Makino Kotaro Tominaga Junji Kolobov Alexander V. Fons Paul Hase Muneaki
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.101, no.23, pp.232101, 2012-12
- 被引用文献数
- 15
We report the optical perturbation of atomic arrangement in the layered in GeTe/Sb2Te3 phase change memory material. To observe the structural change, the coherent A1 mode of GeTe4 local structure was investigated at various polarization angles of femtosecond pump pulses with the fluence at ≤ 78 μJ/cm2. p-polarization found to be more effective in inducing the A1 frequency shift that can be either reversible or irreversible depending on the pump fluence. The predominant origin of this shift is attributed to rearrangement of Ge atoms driven by anisotropic dissociation of the Ge-Te bonds along the [111] axis after the p-polarized pulse irradiation.