For a material to be a good thermoelectric cooler, it must have a high thermoelectric figure of merit ZT. Much of the recent work on thermoelectric materials has focused on the ability of heterostructures and quantum confinement to increase efficiency over bulk materials

[5–7]. So far, the thermoelectrical materials used in applications have all been in bulk (3D) and thin film (2D) forms. However, Hicks et al. had pointed out that low-dimensional materials (for example 1D for nanowires) have better efficiency than bulk and thin film forms due to low-dimensional effects on both charge carriers and lattice waves [8]. However, since the 1960s, only slow progress has been XMU-MP-1 supplier made in enhancing ZT [9], either in BiSbTe-based alloys or in other thermoelectric material. The validity of attaining higher ZT value in low dimension systems has been experimentally demonstrated on Bi2Te3/Sb2Te3 superlattices [10] and on PbTe/PbSeTe quantum dots [2] with ZT of approximately 2.4 and 1.6, respectively, at 300 K. Therefore, nanowires are potentially good thermoelectrical systems for application. In the past, electrochemical deposition was a useful method to deposit the materials in different morphologies, including thin films and nanowires [11]. The successfully practical applications of the nanostructured

thermoelectric devices must investigate a cost-effective and high-throughput fabrication process. In the past, many various techniques,

C646 including chemical vapor deposition Adenosine triphosphate [10], molecular beam epitaxy [12], vapor-liquid-solid growth process [13], and hydrothermal process [14], had been applied to synthesize nanowire-, nanotube-, or thin film-structured thermoelectric materials. Compared to those methods, electrodeposition is one the most cost-effective techniques to fabricate the nanostructured materials [15]. In this study, commercial honeycomb structure anodic aluminum oxide (AAO) nanotube arrays were used as the templates, and the cyclic voltammetry process was used as the method to deposit the (Bi,Sb)2 – x Te3 + x -based thermoelectric nanowires. At first, potentiostatic deposition process and two different electrolyte formulas were used to find the effects of ionic concentrations on the composition fluctuation of the deposited (Bi,Sb)2 – x Te3 + x materials. After finding the better deposition parameters, AAO thin films with a nanotube structure were used a template to fabricate the (Bi,Sb)2 – x Te3 + x nanowires by means of the pulse deposition process. We would show that the (Bi,Sb)2 – x Te3 + x nanowires with (Bi + Sb)/Te atomic ratio close to 2/3 could be successfully grown. Methods For the AAO templates, an annealed high-purity (99.99%) aluminum foil was electropolished in a mixture of HClO4 (25% in volume ratio) and C2H5OH (75%) until the root mean square surface roughness of a typical 10 μm × 10 μm area was 1 nm.