Effect of asymmetric concentration profile on thermal conductivity in Ge/SiGe superlattices
Hahn, Konstanze R. (Universita degli Studi Di Cagliari. Dipartimento di Fisica)
Cecchi, Stefano (Paul-Drude-Institut für Festkörperelektronik. Department of Epitaxy)
Colombo, Luciano (Institut Català de Nanociència i Nanotecnologia)

Data:	2016
Resum:	The effect of the chemical composition in Si/Ge-based superlattices on their thermal conductivity has been investigated using molecular dynamics simulations. Simulation cells of Ge/SiGe superlattices have been generated with different concentration profiles such that the Si concentration follows a step-like, a tooth-saw, a Gaussian, and a gamma-type function in direction of the heat flux. The step-like and tooth-saw profiles mimic ideally sharp interfaces, whereas Gaussian and gamma-type profiles are smooth functions imitating atomic diffusion at the interface as obtained experimentally. Symmetry effects have been investigated comparing the symmetric profiles of the step-like and the Gaussian function to the asymmetric profiles of the tooth-saw and the gamma-type function. At longer sample length and similar degree of interdiffusion, the thermal conductivity is found to be lower in asymmetric profiles. Furthermore, it is found that with smooth concentration profiles where atomic diffusion at the interface takes place the thermal conductivity is higher compared to systems with atomically sharp concentration profiles.
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Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Asymmetric concentration ; Asymmetric profile ; Atomic diffusions ; Chemical compositions ; Concentration profiles ; Gaussian functions ; Molecular dynamics simulations ; Smooth functions
Publicat a:	Applied physics letters, Vol. 108, issue 20 (May 2016) , art. 203102, ISSN 1077-3118

DOI: 10.1063/1.4949491

6 p, 992.9 KB

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