The Thermoelectric Properties of Sub-50 nm Silicon Nanowires

Samarelli, A., Ferre Llin, L., Mirza, M. M. , MacLaren, D. and Paul, D. (2013) The Thermoelectric Properties of Sub-50 nm Silicon Nanowires. In: 39th International Conference on Micro and Nano Engineering (MNE), London, UK, 16-19 Sep 2013,

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Arrays of freestanding Si nanowires have been fabricated by electron beam lithography, low-damage dry etch and thermal oxidation. Integrated heaters, thermometers and electrical contacts were microfabricated to allow the thermoelectric properties to be measured. 45 nm wide n-type Si nanowires demonstrate electrical conductivities of 20,300 S/m, thermal conductivities of 7.8 W/mK and Seebeck coefficients of –271 μV/K resulting in a ZT of 0.057 at 300 K. This represents an enhancement over bulk silicon with comparable doping of a factor of 117. As fuel prices increase, there is significant interest in sustainable energy sources. Thermoelectric applications include powering autonomous sensors and harvesting heat from car exhausts to replace alternators and improve fuel consumption. Thermoelectric materials convert thermal energy into electrical energy using the Seebeck effect. The thermodynamic conversion efficiency is related to the figure of merit ZT = a2sT/k where a is the Seebeck coefficient, s is the electrical conductivity, T is the temperature and k is the thermal conductivity. High performance thermoelectric materials have a high s and low k. Unfortunately the Wiedemann- Franz rule links s and k in 3D making optimization of bulk materials difficult. Low dimensional structures allow enhancements to s, a and k including the potential to relax Wiedemann-Franz as first suggested by Dresselhaus [1] and initial experiments suggest nanowires can produce significant enhancements [2].

Item Type:Conference Proceedings
Glasgow Author(s) Enlighten ID:Samarelli, Mr Antonio and Mirza, Dr Muhammad M A and Ferre Llin, Dr Lourdes and Paul, Professor Douglas and MacLaren, Dr Donald
Authors: Samarelli, A., Ferre Llin, L., Mirza, M. M., MacLaren, D., and Paul, D.
Subjects:Q Science > QC Physics
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
College of Science and Engineering > School of Physics and Astronomy
Research Group:Semiconductor Device Group and James Watt Nanofabrication Centre
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