Crystal growth of narrow gap semiconductors for thermoelectric applications

Recently, there has been a growing interest in small integrated cooling units. This prompted us to establish a screening program for the search of new efficient thermoelectric materials requiring the optimization of figure of merit. Preparation and crystal growth experiments on possible thermoelectric compounds: TiNiSn, ZrNiSn, CoSb/sub 3/, SrAs/sub 3/, /spl beta/-FeSi/sub 2/, FeSi, NiS, La/sub 3/Cu/sub 3/Sb/sub 4/, Ce/sub 3/Cu/sub 3/Sb/sub 4/, Gd/sub 3/Cu/sub 3/Sb/sub 4/ are presented. Single crystals of congruently melting compounds were obtained by the Czochralski or Bridgman techniques. The peritectic decomposing compounds were prepared by flux-growth. Low defect crystals were obtained by vapor transport. Whenever it was possible, more than one technique was studied for the preparation of the same compound. Transport properties and thermoelectric properties were measured and discussed.