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Vol.38, No.1, 165 ~ 172, 2000
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| Title |
| Pesearch Paper / Electronic , Magnetic & Optical Matrials : Effects of Excess Te Addition and Growth Rate on Thermoelectric Properties of 22.5% Bi2Te3-77% Sb2Te3 Single Crystals |
| 현도빈Dow Bin Hyun,하헌필Heon Phil Ha,황종승Jong Seung Hwang,오태성Tae Sung Oh |
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| Abstract |
| The thermoelectric properties of the p-type 22.5% Bi₂Te₃-77.5% Sb₂Te₃ single crystals, grown by the zone melting method, have been studied with changing the amount of excess Te up to 6 wt% and the growth rate from 0.1 to 0.5 ㎜/min. The Seebeck coefficient and electrical resistivity along the ingot growth direction were significantly affected by the amount of excess Te and growth rate due to the retrograde solubility of Te and the segregation of free Te in the matrix. The 5 wt% excess Te-doped 22.5% Bi₂Te₃-77.5% Sb₂Te₃ single crystal, grown at 0.1 ㎜/min, exhibited a figure-of-merit higher than 3.2×10^(-3)/K. However, the figure-of-merit at the last frozen part of such ingot decreased significantly due to the segregation of free Te. With charging 5 wt% excess Te-doped 22.5% Bi₂Te₃-77.5% Sb₂Te₃ at the first-to-freeze part and 0.2 wt% Te-deficient 22.5% Bi₂Te₃-77.5% Sb₂Te₃ at the last-to-freeze part, p-type single crystals with the figure-of-merit higher than 3.2×10^(-3)/K throughout the whole ingot were obtained. |
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