The cross-plane thermoelectric properties of p-Ge/Si0.5Ge0.5 superlattices

Ferre Llin, L. et al. (2013) The cross-plane thermoelectric properties of p-Ge/Si0.5Ge0.5 superlattices. Applied Physics Letters, 103(14), Art. 143507. (doi: 10.1063/1.4824100)

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The electrical conductivity, Seebeck coefficients, and thermal conductivities of a range of p-type Ge/Si0.5 Ge 0.5 superlattices designed for thermoelectric generation and grown by low energy plasma enhanced chemical vapor deposition have been measured using a range of microfabricated test structures. For samples with barriers around 0.5 nm in thickness, the measured Seebeck coefficients were comparable to bulk p-SiGe at similar doping levels suggesting the holes see the material as a random bulk alloy rather than a superlattice. The Seebeck coefficients for Ge quantum wells of 2.85 ± 0.85 nm increased up to 533 ± 25 μV/K as the doping was reduced. The thermal conductivities are between 4.5 to 6.0 Wm−1K−1 which are lower than comparably doped bulk Si0.3 Ge 0.7 but higher than undoped Si/Ge superlattices. The highest measured figure of merit ZT was 0.080 ± 0.011 obtained for the widest quantum well studied. Analysis suggests that interface roughness is presently limiting the performance and a reduction in the strain between the quantum wells and barriers has the potential to improve the thermoelectric performance.

Item Type:Articles (Letter)
Glasgow Author(s) Enlighten ID:Ferre Llin, Dr Lourdes and Dobson, Dr Phil and Samarelli, Mr Antonio and Paul, Professor Douglas
Authors: Ferre Llin, L., Samarelli, A., Cecchi, S., Etzelstorfer, T., Müller Gubler, E., Chrastina, D., Isella, G., Stangl, J., Weaver, J.M.R., Dobson, P.S., and Paul, D.J.
Subjects:Q Science > QC Physics
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Applied Physics Letters
ISSN (Online):1077-3118

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