Electrical and Structural Real-Time Changes in Thin Thermoelectric (Bi^sub 0.15^Sb^sub 0.85^)^sub 2^Te^sub 3^ Films by Dynamic Thermal Treatment

• Published in: Journal of electronic materials Vol. 39; no. 9; p. 1408
• Main Authors: Rothe, K, Stordeur, M, Heyroth, F, Syrowatka, F, Leipner, H S
• Format: Journal Article
• Language: English
• Published: Warrendale Springer Nature B.V 01-09-2010
• Subjects: Generators; Heating; Temperature; Thin films
• ISSN: 0361-5235; 1543-186X

A recent trend in thermoelectrics is miniaturization of generators or Peltier coolers using the broad spectrum of thin-film and nanotechnologies. Power supplies for energy self-sufficient micro and sensor systems are a wide application field for such generators. It is well known that thermal treatment of as-deposited p-type (Bi^sub 0.15^Sb^sub 0.85^)^sub 2^Te^sub 3^ films leads to enhancement of their power factors. Whereas up to now only the start (as-deposited) and the end (after annealing) film stages were investigated, herein for the first time, the dynamical changes of sputter-deposited film properties have been observed by real-time measurements. The electrical conductivity shows a distinct, irreversible increase during a thermal cycle of heating to about 320°C followed by cooling to room temperature. The interpretation of the Seebeck and Hall coefficients points to an enhancement in Hall mobility after annealing. In situ x-ray diffractometry shows the generation of an additional Te phase depending on temperature. This is also confirmed by energy-dispersive x-ray microanalysis and the corresponding mapping by scanning electron microscopy. It is presumed that the Te enrichment in a separate, locally well-defined phase is the reason for the improvement in the integral film transport properties. [PUBLICATION ABSTRACT]