Optimal thermoelectric figure of merit of SiGe core-shell nanowires

Nano Research 8, 2611 - 2619 (2015)

Optimal thermoelectric figure of merit of SiGe core-shell nanowires

Kaike Yang, Andres Cantarero, Angel Rubio, Roberto D'Agosta

We investigate the thermoelectric energy conversion efficiency of Si and Ge nanowires. In particular, we consider Si/Ge core-­shell nanowires. We show how the presence of a thin Ge shell in a Si core nano-­wire increases the overall figure of merit. We find the optimal thickness of the Ge shell in terms of providing the largest figure-­of-­merit of the devices. We consider also Ge core/Si shell nanowires and we show that there is not an optimal thickness of the shell, since the figure-of-­merit is a monotonously decreasing function of the radius of the nano-­wire. Finally, we verify the empirical law that relates the electron energy gap to the optimal working temperature, the one maximising the efficiency of the device.

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http://dx.doi.org/10.1007/s12274-015-0766-2

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