Ternary, single-crystalline Bi₂ (Te, Se)₃ nanowires grown by electrodeposition

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• 作者：Praveen Kumar^a ; ^{praveen.kumar@uni-tuebingen.de} ; Michael Pfeffer^a ; Nicola Peranio^a ; Oliver Eibl^a ; Svenja Bä ; ß ; ler^b ; Heiko Reith^b ; Kornelius Nielsch^b ; ^c
• 关键词：Nanowire ; Thermoelectrics ; Electrodeposition ; Transmission electron microscopy ; Structure&minus ; property relationship
• 刊名：Acta Materialia
• 出版年：2017
• 出版时间：15 February 2017
• 年：2017
• 卷：125
• 期：Complete
• 页码：238-245
• 全文大小：2090 K
• 卷排序：125

文摘

Single-crystalline, ternary n-type Bi2Te3−ySey nanowires are grown by potential-pulsed electrochemical deposition with 45 nm, 70 nm and 195 nm nominal diameters. Electrical conductivity and thermopower of the nanowires are measured. TEM analysis proves that the nanowires grow along the [110] direction with the c-axis perpendicular to the nanowire axis and yield diameters of 70–80 nm (nominally 45 nm, #1), 85–100 nm (70 nm, #2) and 265–325 nm (195 nm, #3). This yields electronic transport along the basal plane of the Bi2Te3 crystal structure. Chemical composition of the nanowires is measured by TEM-EDX spectroscopy.These nanowires show exciting electronic properties, like Shubnikov-de-Haas oscillations at low temperatures, summarized in another paper. All nanowires investigated are oxygen contaminated but single crystalline, precipitates are only observed in #3 nanowire. The stoichiometry offset and fluctuations of #2 nanowire are significantly larger compared to #1 and #3 nanowires. The thermopower correlates with these structural data, the smallest thermopower is found for #2 nanowire and a similar, larger thermopower is found for #1 and #3 nanowires.For #1 and #2 nanowires dislocation densities of about 7.8 × 1010 cm−2 and 1.0 × 1011 cm−2 are observed, respectively, wherein dislocations lie parallel to the growth direction. While for #3 nanowire, a dislocation density of 1.2 × 1010 cm−2 is observed and dislocations are oriented perpendicular to the growth direction. This reduces the heat conductivity of the #3 nanowire due to phonon scattering on the strain field of dislocations.