Investigation on the homogeneity of pulsed electrochemically deposited thermoelectric films with synchrotron μ-XRF, μ-XRD and μ-XANES

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2013-01, Vol.1 (13), p.4215-4220
• Main Authors: Reinsberg, Klaus-Georg, Schumacher, Christian, Zastrow, Sebastian, Nielsch, Kornelius, Broekaert, José A. C., Fittschen, Ursula E. A.
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c3ta01480k

Thermoelectric materials are able to generate a voltage and current, when subjected to a gradient of temperature. A cost and time efficient production of thermoelectric units is the goal for future miniaturized thermoelectric generators based on thin films up to 200 mu m. A comprehensive analysis of chemical and physical properties is a crucial part of the developments. One of the key parameters for the materials' physical properties is the Seebeck coefficient (S= Delta U/ Delta T), which is the generated voltage for a given temperature difference. To determine the origin of a variation of S, which is found for thermoelectric materials, such as Bi sub(2)Te sub(3) and Sb sub(2)Te sub(3) an investigation on their stoichiometric and structural homogeneity is presented. Nondestructiveness and a mesoscopic spatial resolution are the key parameters which allow for repetitive analyses. The samples are electrochemical deposits of 10 mu m thickness on Si wafers. Micro-X-ray fluorescence ( mu -XRF) and micro-X-ray diffraction analysis ( mu -XRD) with 15 mu m spot size are performed simultaneously with focused synchrotron X-ray radiation at 30 keV. Additionally micro-X-ray absorption near edge structure ( mu -XANES) measurements are performed. No inhomogeneity is detectable for samples prepared under optimized, pulsed potential conditions. Instead an indication of a correlation between the thermopower (S) variations and sample thickness variations is found.