Tailoring Thermal Conductivity of Ge/Si Core-Shell Nanowires

S Sarikurt and C Sevik and A Kinaci and JB Haskins and T Cagin, Proceedings of the TMS Middle East - Mediterranean Materials Congress on Energy and Infrastructure Systems (MEMA 2015), 433-440 (2015).

DOI: 10.1002/9781119090427.ch46

Low-dimensional nanostructured materials show large variation in their thermal transport properties. Here, we investigate the influence of core-shell architecture on nanowire ( NW) thermal conductivity using molecular dynamics with Tersoff potentials Si-Ge, to design structures with desired thermal conductivity for thermoelectric device applications. To explore the parameter space, we have calculated thermal conductivity values of Ge/Si core-shell NWs having different lengths, cross-section sizes and Ge concentrations at several temperatures. We have found that ( 1) increasing the cross-sectional area of pure Si NW causes an increase in thermal conductivity ( 2) increasing the Ge core size in the Ge/Si structure results in a decrease in the thermal conductivity values at 300. ( 3) there is no significant variation in the thermal conductivity of Si NW for temperature values larger than 300. ( 4) the predicted thermal conductivity around 10 W m(-1)K(-1) is still larger than the value convenient for thermoelectric applications.

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