Ordered nanowires based on V–VI materials: From synthesis in organic electrolytes to electrical characterization

Abstract

Thermoelectric nanowires have been predicted theoretically, and in a few cases shown experimentally, to have superior properties compared to their bulk counterparts due to quantum confinement. We present the synthesis of chalcogenide nanowires A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (A = Bi, Sb; B = S, Se, Te) by electrochemical deposition into highly ordered porous Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> membranes as nanotemplates. The narrow pore size distribution of the templates reproducibly yields nanowires of very homogeneous aspect ratio upon electrodeposition into the pores. The thermoelectric nanowires presented here were deposited from nonaqueous electrolytes based on Bi <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> and S (and their heavier counterparts). SEM investigations on released nanowires showed the homogeneous growth behaviour of the material. We were able to determine the Seebeck coefficient of nanowire ensembles of various V-VI materials embedded in the porous template. Furthermore we could obtain current-voltage curves for Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> from a single nanowire contacted using the focused ion beam technique.