Abstract
We perform lattice dynamics calculations (LD) on silicon/germanium interfaces using ab initio interatomic force constants to predict the interfacial phonon transmission as a function of both phonon frequency and the transmission angle. We carry out a spectral and angular analysis to quantify the contribution of each phonon mode in a given scattering direction. The effect of the interaction range was studied at this interface by taking account of more or less atom layers across the interface. Moreover, we were able to predict the thermal boundary conductance (TBC) as a function of the transmission angle and temperature as well. Our results show that, the thermal energy transmission is highly anisotropic while thermal energy reflection is almost isotropic. In addition, we found that it seems there is a global critical angle of transmission beyond which almost no thermal energy is transmitted. This can be used to device high pass phonon filter via changing the orientation of the interface.
Highlights
Since the discovery of thermal resistance at the interface between two media by the pioneering experimental work of Kapitza on superfluid helium/solid interfaces [1], many theoretical attempts have been to understand interfacial heat transport
Theoretical Model we present the main equations used in lattice dynamics calculations (LD) for a perfect interface between two diamond-like structure solids in three-dimensions
We present the results obtained by performing the LD calculations on Si/Ge interface as described in the previous section
Summary
Since the discovery of thermal resistance at the interface between two media by the pioneering experimental work of Kapitza on superfluid helium/solid interfaces [1], many theoretical attempts have been to understand interfacial heat transport. To completely describe the transmission at the interface, we need a set of 6ˆN equations, where N is the number of the interacting atomic layers taken into account.
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