Thermal boundary conductance in heterostructures studied by ultrafast electron diffraction

We report measurements of the transient structural response of weakly photo-excited thin films of BiFeO3, Pb(Zr,Ti)O3, and Bi and time-scales for interfacial thermal transport. Utilizing picosecond x-ray diffraction at a 1.28 MHz repetition rate with time resolution extending down to 15 ps, transient changes in the diffraction angle are recorded. These changes are associated with photo-induced lattice strains within nanolayer thin films, resolved at the part-per-million level, corresponding to a shift in the scattering angle three orders of magnitude smaller than the rocking curve width and changes in the interlayer lattice spacing of fractions of a femtometer. The combination of high brightness, repetition rate, and stability of the synchrotron, in conjunction with high time resolution, represents a novel means to probe atomic-scale, near-equilibrium dynamics.

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“…This time-scale is comparable to acoustic propagation time through the film (using c l = 1.9 nm/ps (Ref. 35)). Motivated by Refs.…”

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confidence: 69%

Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution

Kozina

Wittenberg

et al. 2014

Structural Dynamics

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“…The transient surface temperature evolution of the thin Bi-films upon excitation with ultrashort laser pulses was studied by ultrafast electron diffraction [7,[13][14][15]. A commercial regenerative amplifier system (Legend, Coherent) provides an output power of 2.3 W at a repetition rate of 5 kHz.…”

Section: Methodsmentioning

confidence: 99%

“…Phonon waves with incident angles larger than the φ max are totally reflected at the interface and do not contribute to the heat transfer across the interface. The thermal boundary conductance calculated within the AMM is between 1350 (W/cm 2 K) for 80 K and 1450 (W/cm 2 K) for 300 K [7]. Taking mode conversion into account only 1 of 100 phonons is able to leave the Bi-film.…”

Section: Introductionmentioning

confidence: 99%

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Transient Cooling of Ultrathin Epitaxial Bi(111)-Films on Si(111) Upon Femtosecond Laser Excitation Studied by Ultrafast Reflection High Energy Electron Diffraction

et al. 2009

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With time resolved ultrafast electron diffraction the cooling process across the interface between a thin film and the underlying substrate was studied after excitation with short laser pulses. From the exponential decay of the surface temperature evolution a thermal boundary conductance of 1430 W/(cm 2 K) is determined for a 9.7 nm thin Bi(111) film on Si(111). A linear dependence between laser fluence and initial temperature rise was measured for film-thicknesses between 2.5 nm and 34.5 nm. The ratio of initial temperature rise and laser fluence for different film-thicknesses is compared to a model taking multilayer optics into account. The data agree well with this model.

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“…The transient evolution of the excitation and relaxation processes is determined by diffraction from a time delayed electron pulse (probe). The demand for surface sensitivity in combination with a high temporal resolution makes the use of high energy electrons under gracing incidence the versatile tool for time-resolved surface science 17–20 . In a recent work, Gulde et al demonstrated that also picosecond pulses of low energy electrons can be employed to resolve the structural dynamics in a single polymer layer supported by graphene in transmission geometry 21 …”

Section: Introductionmentioning

confidence: 99%

Spot profile analysis and lifetime mapping in ultrafast electron diffraction: Lattice excitation of self-organized Ge nanostructures on Si(001)

Frigge

Hafke

Tinnemann

et al. 2015

Structural Dynamics

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Ultrafast high energy electron diffraction in reflection geometry is employed to study the structural dynamics of self-organized Germanium hut-, dome-, and relaxed clusters on Si(001) upon femtosecond laser excitation. Utilizing the difference in size and strain state the response of hut- and dome clusters can be distinguished by a transient spot profile analysis. Surface diffraction from {105}-type facets provide exclusive information on hut clusters. A pixel-by-pixel analysis of the dynamics of the entire diffraction pattern gives time constants of 40, 160, and 390 ps, which are assigned to the cooling time constants for hut-, dome-, and relaxed clusters.

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Thermal boundary conductance in heterostructures studied by ultrafast electron diffraction

Cited by 37 publications

References 22 publications

Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution

Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution

Transient Cooling of Ultrathin Epitaxial Bi(111)-Films on Si(111) Upon Femtosecond Laser Excitation Studied by Ultrafast Reflection High Energy Electron Diffraction

Spot profile analysis and lifetime mapping in ultrafast electron diffraction: Lattice excitation of self-organized Ge nanostructures on Si(001)

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