Electrodeposition of Alloyed p-and n-type Bi 2 Te 3 Nanowires Maksudul Hasan 1 , Ryan Enright 2 , Eric Dalton 3 , Domhnaill Hernon 2 and Kafil M. Razeeb 1,* 1 Tyndall National Institute, University College Cork, Lee Maltings, Dyke Parade, Cork, Ireland 2 Thermal Management Research Group, Efficient Energy Transfer (ηET) Dept., Bell Labs Ireland, Alcatel Lucent Ireland Ltd., Blanchardstown Business & Technology Park, Snugborough Rd., Blanchardstown, Dublin 15, Ireland 3 Stokes Institute, University of Limerick, Limerick, Ireland *Corresponding author: kafil.mahmood@tyndall.ie Solid-state cooling and power generation based on thermoelectric Seebeck and Peltier effects have potential applications in waste-heat recovery, air conditioning and refrigeration. The idea of increasing ZT value using the same material but in a lower dimensional structures was introduced by Hicks and Dresselhaus in 1993 1 . During the past decade several groups 2-4 have reported enhancement in the ZT values (>1) with low dimensional structures mainly due to the reduced phonon thermal conductivity. However, quantum confinement of electronic carriers to improve thermoelectric performance has yet to be realized. Bismuth and antimony telluride based materials are considered to be the best for thermoelectric applications in the temperature range of 200 to 400 K. Bi 2 Te 3 alloys exhibit the highest ZT near room temperature, and are the leading candidates for low temperature thermoelectric applications. Furthermore, it is expected that forming nanowires of Bi 2 Te 3 to realize a 1D geometry will increase the ZT value due to quantum size effects 5, 6 . Realizing these materials for practical application is challenging since the current state- of-the-art materials and fabrication processes are difficult to scale up to practically useful device dimensions and costs are significant. Bi 2 Te 3 thin films have been prepared by various techniques, such as pulsed laser deposition (PLD), metal-organic chemical vapour deposition (MOCVD), and molecular beam epitaxy (MBE). Recently, electrodeposition has attracted wide attention in the fabrication of Bi 2 Te 3 -based thermoelectric devices because of its low cost, simple equipment, easy control and high productivity. In this paper, we report the pulsed electrodeposition of Bi 2 Te 3 nanowires from a single aqueous electrolyte using track-etched polycarbonate membranes as templates. The deposition of the nanowires was controlled by tuning the applied potential waveforms and pulse times. Distinctive reduction potentials were observed corresponding to the formation of p- and n-type Bi 2 Te 3 nanowires (see Fig. 1). We demonstrate the influence of the pulse parameters on the stoichiometry, crystallographic orientation, grain size and boundary, and thermal and electrical conductivity of both p- and n-type Bi 2 Te 3 nanowires. Fig. 1 (a) CV of Bi 2 Te 3 electrolyte, (b) cross sectional and (c) top view SEM images of the as- prepared Bi 2 Te 3 nanowire arrays. Inset of (b) showing the grain size effect of the deposit by tuning the applied potential. References: 1. Hicks, L. D.; Dresselhaus, M. S. Physical Review B 1993, 47, (24), 16631-16634. 2. Venkatasubramanian, R.; Siivola, E.; Colpitts, T.; O'Quinn, B. Nature 2001, 413, (6856), 597-602. 3. Harman, T. C.; Taylor, P. J.; Walsh, M. P.; LaForge, B. E. Science 2002, 297, (5590), 2229-2232. 4. Hsu, K. F.; Loo, S.; Guo, F.; Chen, W.; Dyck, J. S.; Uher, C.; Hogan, T.; Polychroniadis, E. K.; Kanatzidis, M. G. Science 2004, 303, (5659), 818-821. 5. Lin, Y. M.; Dresselhaus, M. S. Physical Review B 2003, 68, (7). 6. Dames, C.; Chen, G. Journal of Applied Physics 2004, 95, (2), 682-693. (a) (b) (c)