Ultrafast dephasing of coherent optical phonons in atomically controlled GeTe/Sb${}_2$Te${}_3$ superlattices

Abstract

Femtosecond dynamics of coherent optical phonons in GeTe/Sb${}_2$Te${}_3$ superlattices (SLs), a new class of semiconductor SLs with three different states, have been investigated by using a reflection-type pump-probe technique at various lattice temperatures. The time-resolved transient reflectivity (TR) obtained in as-grown SLs exhibits the coherent A${}_1$ optical modes at 5.10 THz and 3.78 THz, while only the single A${}_1$ mode at 3.68 THz is observed in annealed SLs. The decay rate of the A${}_1$ mode in annealed SLs is strongly temperature dependent, while that in as-grown SLs is not temperature dependent. This result indicates that the damping of the coherent A${}_1$ phonons in amorphous SLs is governed by the phonon-defect (vacancy) scattering rather than the anharmonic phonon-phonon coupling.

5 pages, 5 figures

References in corpus (4)

• Evidence for a Structurally-driven Insulator-to-metal Transition in VO2: a View from the Ultrafast Timescale
• Dynamical, dielectric, and elastic properties of GeTe
• Forcibly driven coherent soft phonons in GeTe with intense THz-rate pump fields
• Ultrafast Critical Dynamics of Ferroelectric Phase Transition in Pb${}_{1-x}$Ge${}_x$Te

Cited by in corpus (8)

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• Coherent phonon study of (GeTe)${}_l$(Sb${}_2$Te${}_3$)${}_m$ interfacial phase change memory materials
• Thermal conductivity of GeTe/Sb${}_2$Te${}_3$ superlattices measured by coherent phonon spectroscopy
• Development of the temperature-dependent interatomic potential for molecular dynamics simulation of metal irradiated with an ultrashort pulse laser
• Coherent gigahertz phonons in Ge${}_2$Sb${}_2$Te${}_5$ phase-change materials