Electrical and Structural Real-Time Changes in Thin Thermoelectric (Bi0.15Sb0.85)2Te3 Films by Dynamic Thermal Treatment |
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Authors: | K. Rothe M. Stordeur F. Heyroth F. Syrowatka H. S. Leipner |
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Affiliation: | (1) School of Electronics and Information Engineering, Kunsan National University, San 68, Miryong-dong, Kunsan, Jeollabuk-do, South Korea, 573-701 |
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Abstract: | 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 (Bi0.15Sb0.85)2Te3 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. |
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