No abstract

Sb2Te3 has recently been an object of intensive research since its promising applicability in thermoelectric, in phase-change memory devices and as a topological insulator. In this work we report highly textured Sb2Te3 thin films, grown by atomic layer deposition on Si/SiO2 wafers based on the reaction of SbCl3 and Te(SiMe3)2. The low deposition temperature at 80° C allows for the pre-patterning of the Sb2Te3 by standard lithography processes. A platform to characterize the Seebeck-coefficient S, the electrical conductivity σ as well as the Hall coefficient RH on the same film has been developed. Comparing all temperature-dependent transport properties, three different conductive regions in the temperature range of 75 to 300 K are found. Room temperature values of S = 146 V K -1 ,  = 10 4 S m -1 and mobility  = 270.5 x 10 4 m 3 V -1 s -1 are determined. The low carrier concentration in the range of n = 2.4 x 10 18 cm -3 at 300 K quantifies the low defect content of the Sb2Te3 thin films.

A systematic optimization of p-type Sb 2 Te 3 thermoelectric films made by potentiostatic electrodeposition on Au and stainless steel substrates is presented. The influence of the preparative parameters of deposition voltage, concentration, and the deposition method are investigated in a nitric acid solution. As a postdeposition step, the influence of annealing the films is investigated. The use of a potential-controlled millisecond-pulsed deposition method could improve both the morphology and the composition of the films. The samples are characterized in terms of composition, crystallinity, Seebeck coefficient, and electrical resistivity. Pulsed-deposited films exhibit Seebeck coefficients of up to 160 μV K −1 and an electrical conductivity of 280 S cm −1 at room temperature, resulting in power factors of about 700 μW m −1 K −2 . After annealing, power factors of maximum 852 μW m −1 K −2 are achieved. Although the annealing of DC-deposited films significantly increased the power factor, they do not reach the values of the pulseddeposited films in the preannealing state. Structural analysis is performed with X-ray diffraction and shows the crystalline structure of Sb 2 Te 3 films. The performance is tuned by annealing of deposited films up to 300 °C under He atmosphere while performing in-situ X-ray diffraction and resistivity measurements. The chemical analysis of the films is performed by inductively coupled plasma optical emission spectroscopy (ICP-OES) as well as scanning electron microscope energy dispersive X-ray analysis (SEM-EDX).

This Letter reports on temperature‐dependent electrical measurements of single Bi0.92Sb0.08 nanowires with diameters between 220 nm and 350 nm. The magnetoresistance effect under transverse magnetic fields of ±2 T and the Seebeck coefficient S are measured in the temperature range of 50–300 K. Additionally, the influence of an annealing step on the transport properties is investigated. The as‐prepared wires show heterogeneous temperature dependent behavior, whereas the annealed wires show semiconductive behavior. The room temperature value of the resistivity of the wires is between 2 × 10–6 Ωm and 1.4 × 10–5 Ωm. Magnetoresistance effects up to 15% at 50 K for the as‐prepared nanowires and up to 23% for the annealed wires are observed. The temperature dependent Seebeck coefficient of single wires is determined. The as‐prepared wires show a rise of the absolute value of S with temperature and it seems to saturate at room temperature. In contrast to this, the annealed wires show a linear increase of S. The room temperature values of S are –55 µV K–1 and –45 µV K–1, respectively. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)