Direct Electrodeposition of Highly Dense 50 nm Bi₂Te_3-<i>_y</i>Se<i>_y</i> Nanowire Arrays

Abstract

Films and arrays of 200 and 50 nm diameter wires of Bi2Te3-xSex have been electrodeposited in the following general reaction: 2Bi3+ + (3−y)HTeO2+ + (y)H2SeO3 + (9+y)H+ + 18e- → Bi2Te3-ySey + (6+y)H2O. Films produced from an electrolyte of 0.0075 M Bi, 0.0090 M Te, and 0.0010 M Se in 1 M HNO3 at a potential of ∼0 V vs Ag/AgCl are single phase with composition Bi2Te2.6Se0.4 as determined by X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. Similar conditions yield arrays of 200 and 50 nm Bi2Te3-ySey wires when deposited into porous alumina templates. The wires are single phase, crystalline, and textured, with up to 85% pore filling.