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Low dimensional materials for thermoelectric energy conversion systems

: Nurnus, J.; Böttner, H.; Künzel, C.; Vetter, U.; Lambrecht, A.; Schumann, J.; Völklein, F.

Materials Week 2002. Proceedings. CD-ROM
Frankfurt: Werkstoffwoche-Partnerschaft GbRmbH, 2002
ISBN: 3-88355-314-X
8 pp.
Materials Week <2002, München>
Conference Paper
Fraunhofer IPM ()
Wismutlegierung; Tellurzusatz; Selenzusatz; Thermoelement; Wärmebeständigkeit; Berechnung; Kühlkörper; Thermosäule; Epitaxialschicht; Lötmittel; Polyester; Kleber

For the first time thermopile detectors consisting of MBE grown V-VI epitaxial bulk- and SL-films transferred onto a low thermal conductivity foil substrate were prepared. The sensitivities and specific detectivities D * of single Bi2(Te,Se )3-Sb2Te3-thermocouples determined under vacuum conditions were S ca.= 10 V W (exp -1) and D* ca. = 1x10 (exp 9) cm Hz (exp 1/2)W(exp-1). One way to improve the thermal resistance between the heat sink and the foil substrate is to replace the actually used polyester glue by a metallic solder. By doing so S and D * -values close to the calculated ones (S ca. = 40 V W (exp -1) , D* ca. = 2.8 10 9 cm Hz(exp 0.5) W(exp -1) should be within reach. Due to the sensitivity optimized geometry of the investigated structures the response time of the EF-TPD is about 2 seconds. Turning to detectivity optimized structures (calculated values: S ca. =25 V W(exp -1),D* ca. = 3.7x10(exp 9) cmHz(exp 0.5) W(exp -1) response times smaller than 200 ms are achievable due to the reduced leg length. The reported values were measured on large, area single couples. It is obvious that a further improvement of the EF-TPD characteristics is possible by the means of miniaturization. The presented approach for the realization of EF-TPDs is also suitable for IV-VI-based epitaxial films. It is known that IV-VI-layers can be grown up to a thickness of several 10 micron. Using a slightly modified transfer technique, Peltier coolers and thermoelectric generators should be feasible.