Control and Assessment of Structure and Composition in Bismuth Telluride Nanowire Arrays
- PDF / 1,755,531 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 78 Downloads / 253 Views
Control and Assessment of Structure and Composition in Bismuth Telluride Nanowire Arrays M. S. Sander1, A. L. Prieto1, R. Gronsky2, T. Sands2, and A. M. Stacy1 1 Department of Chemistry 2 Department of Materials Science & Engineering University of California, Berkeley, CA 94720
ABSTRACT Due to effects of reduced dimensionality, Bi2Te3 nanowires are predicted to have increased thermoelectric efficiency relative to bulk Bi2Te3, one of the most efficient thermoelectric materials known. High-density arrays of nanowires have desirable characteristics for accessing nanowire properties in potential applications and also allow for facile nanowire property assessment. Here we describe a fabrication method to produce Bi2Te3 nanowire arrays by direct current electrochemical deposition into porous anodic alumina templates. The characteristics of the arrays have been assessed to determine the composition and structure in the arrays as well as in individual nanowires. The fabricated arrays have a high-density of uniform diameter (~40nm), high aspect ratio wires that are stoichiometric, polycrystalline Bi2Te3.
INTRODUCTION Wires with diameters on the order of a few tens of nanometers or less have interesting properties due to the two-dimensional confinement of their charge carriers, along with other lowdimensional effects, including increased phonon scattering. Assemblies of large numbers of nanowires in ordered arrays can potentially be employed in applications requiring high current. To fabricate arrays of nanowires, template-based methods have been employed to produce arrays with a high density of uniform diameter wires.1, 2 In particular, nanoporous anodic alumina templates have been employed to produce arrays of high-density, high aspect ratio, uniform diameter nanowires.3 Bi2Te3 nanowire arrays are of interest for potential thermoelectric applications because bulk Bi2Te3 is known to be an efficient thermoelectric material, and recent theoretical and experimental proof-of-principle studies indicate that low-dimensional structures have improved thermoelectric properties relative to the bulk.4-6 To fabricate the arrays, direct current electrodeposition into porous anodic alumina templates is a good method because electrodeposition can be employed to produce continuous wires with controllable wire composition and structure. In addition, the electrochemical deposition conditions for Bi2Te3 thin films have been well developed.7-10 In this work, we describe the fabrication and characterization of high-density Bi2Te3 by DC electrochemical deposition into porous anodic alumina templates. We have assessed the array structure, including percentage of pore filling and overall wire morphology, as well as the array composition. In addition, we have studied the characteristics of individual nanowires at high spatial resolution. Y8.35.1
EXPERIMENTAL METHODS Nanowire arrays were fabricated by DC electrochemical deposition into porous anodic alumina templates. For nanowire deposition, an Ag film was sputtered onto a piece of Al foil (Alfa
Data Loading...
