Sticking-free growth of bulk Mg/sub 2/Si crystals by the vertical bridgman method and their thermoelectric properties

Abstract

Melt growth of Mg2Si was conducted using the vertical Bridgman growth method. Because magnesium is highly reactive at the growth temperature (1358 K), crucible materials were chosen to avoid chemical reactions and sticking between the crucibles, the molten Mg2Si and magnesium vapor. Crucibles made of alumina, pyrolytic boron nitride (pBN), and hexagonal boron nitride (hBN) were examined. The use of a pBN crucible enabled in the suppression of chemical reactions involving molten Mg2Si and vaporized magnesium at elevated growth temperatures, resulting in no sticking of the grown crystal to the inner wall of the crucible. While the measured conductivity for samples grown using an alumina crucible was n-type for all of the temperatures that were investigated, the samples that were grown using a pBN crucible exhibited p-type conductivity. This correlates closely with unintentional boron incorporation during the growth process.