Electrical and Structural Real-Time Changes in Thin Thermoelectric (Bi0.15Sb0.85)2Te3 Films by Dynamic Thermal Treatment

• Published in: Journal of electronic materials Vol. 39; no. 9; pp. 1408 - 1412
• Main Authors: Rothe, K., Stordeur, M., Heyroth, F., Syrowatka, F., Leipner, H. S.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Boston Springer US 01.09.2010; Springer
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Materials Science; Methods of deposition of films and coatings; film growth and epitaxy; Optical and Electronic Materials; Physics; Solid State Physics; Thermoelectric effects; bismuth telluride; magnetron sputtering; antimony telluride; Thermoelectric properties; thin films; Electrical conductivity; Transport properties; Hall mobility; Microanalysis; Thermal cycle; Hall effect; XRD; Self-energy; Thin films; Thermoelectric materials; Cathode sputtering; Bismuth tellurides; Thermoelectric power; Physical vapor deposition; Sensors; Antimony tellurides; Peltier effect; Temperature dependence; Scanning electron microscopy; Annealing; Cooling; Seebeck effect; Dispersive spectrometry; Real time; Heat treatments; Irreversible processes; Crystal-phase transformations; Transport processes; Miniaturization; X ray diffractometry; Sputter deposition; Nanotechnology
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-010-1325-y

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 0.15 Sb 0.85 ) 2 Te 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.