Accession Number : AD0291739

Title :   SINGLE CRYSTAL BISMUTH TELLURIDE

Corporate Author : AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS

Personal Author(s) : YANG,A.C. ; SHEPHERD,F.D. JR.

Report Date : SEP 1962

Pagination or Media Count : 36

Abstract : Bismuth telluride single crystals were grown by the Czochralski pulling method in a furnace similar to that used by Ainsworth. Bismuth rich and stoichiometric melts led to p-type crystals. Large excesses of Te and doping with Cu2Te led to n-type crystals. Single crystal gwowth was sustained at rates as high as 8.5 cm/hr from p-type melts and 0.5 cm/hr from n-type melts. Growth rates above 3 cm/hr resulted in rectangular cross sections. Those below 1 cm/hr resulted in elliptical cross sections similar to those reported by Ainsworth. Typical cross section dimensions were 1.5 x 0.5 cm. Single crystals have been grown up to 22 cm in length. The variation of thermoelectric power with melt composition was observed for compositions near stoichiometry. Normal p-type thermoelectric powers (seebeck coefficient) ranged from 220 to 260 microvolts/deg C. Normal n-type thermoelectric powers of -15 to -250 microvolts/deg C were obtained. X-ray diffraction lines observed agree with the ASTM index to within experimental error. A transmission edge was observed at approximately 0.145 ev. (Author)

Descriptors :   *INTERMETALLIC COMPOUNDS, *SEMICONDUCTORS, *SINGLE CRYSTALS, *THERMOELECTRICITY, BISMUTH COMPOUNDS, COPPER COMPOUNDS, CRYSTALLIZATION, CRYSTALS, IMPURITIES, MELTING, OPTICS, PHYSICAL PROPERTIES, PREPARATION, ROTATION, TELLURIDES, TEST EQUIPMENT, WAVE PROPAGATION, X RAY PHOTOGRAPHY

Distribution Statement : APPROVED FOR PUBLIC RELEASE