90% Bi2Te3-10% Bi2Se3 단결정의 밴드갭 에너지와 열전특성

하헌필; 현도빈; 황종승; 오태성; Heon-Phil Ha; Dow-Bin Hyun; Jong-Seung Hwang; Tae-Sung Oh

Korean Journal of Materials Research, Vol.9, No.4, 349-354, April, 1999

Export Citation

90% Bi2Te3-10% Bi2Se3 단결정의 밴드갭 에너지와 열전특성

Band-Gap Energy and Thermoelectric Properties of 90% Bi2Te3-10% Bi2Se3 Single Crystals

하헌필, 현도빈, 황종승, 오태성¹

한국과학기술연구원 금속공정연구센터
¹홍익대학교 금속 · 재료공학과

Heon-Phil Ha, Dow-Bin Hyun, Jong-Seung Hwang, and Tae-Sung Oh¹

Division of Metals, Korea Institute of Science and Technology, Seoul 130-650, Korea
¹Dept. of Metallurgy and Materials Science, Hongik University, Seoul 121-791, Korea

초록

Dopant를 첨가하지 않은 시료와 donor dopant로 CdI2를 청가한 90% Bi2Te3-l0% Bi2se3 단결정을 Bridgrnan 법으로 성장시키고 Hall 계수, 전하이동도, 전기비저항, Seebeck 계수, 열전도도 빛 성능지수를 77~600K의 온도범위에서 측정하였다. Dopant를 첨가하지 않은 90% Bi2Te3-10% Bi2Se3 단결정에서 포화정공농도는 5.85 X 10 18 cm-3 이고 degenerate 온도는 127K 이었으며, 전하 이동에 대한 산란인자는 -0.23 이고 전자이동도와 정공이동도의 비 (μe/μh)는 1.45 이었다. 90% Bi2Te3- 10% Bi2Se3 단결정의 0k 에서의 밴드갭 에너지는 0.200 eV 로서 Bi2Te3-Bi2Se3계 단결정에서는 Bi2Se3의 농도가 증가할수록 밴드갭 에너지가 증가하였다. Donor dopant로 CdI2를 첨가한 90% Bi2Te3-10% Bi2Se3 조성의 n 형 단결정에서 성능지수의 최대값은 CdI2를 0.05 wt% 첨가한 경우에 약 230K 에서 3.2x10 -3/K 를 나타내었다.

The temperature dependences of the Hall coefficient, carrier mobility, electrical resistivity, Seebeck coefficient, thermal conductivity, and figure-of-merit of the undoped and CdI2-doped 90% Bi2Te3-10% Bi2Se3 single crystals, grown by the Bridgman method. have been characterized at temperatures ranging fJiom 77K to 600K The saturated carrier conæntration and degenerate temperature of the undoped 90% Bi2Te3-10% Bi3Se3 single crystal are 5.85 x 10 18cm-3 and 127K, respectively. The scattering parameter of the 90% Bi2Te3-10% Bi2Se3 single crystal is determined to be -0.23, and the electron mobility to hole mobility ratio (μ/μ) is 1.45. The bandgap energy at 0K of the 90% Bi2Te3-10% Bi2Se3 single crystal is 0,200 eV. Adding CdI2 as a donor dopant, a maximum figure-of-merit of 3.2x 10-3/K at 230K was obtained for 0.05 wt% CdI2-doped specimen.

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[1] Rowe DM, CRC Handbook of Thermoelectrics, CRC Press, Inc., Boca Raton (1995).

[2] Cope RG, Penn AW, J. Mater. Sci., 3, 103 (1968)

[3] Greenaway DL, Harbeke G, J. Phys. Chem. Solids, 26, 1585 (1965)

[4] Hyun DB, Ha HP, Shim JD, Proc. XI International Conf. Thermoelectrics, Arlington, Texas, 266 (1992).

[5] Black J, Conwell EM, Seigel L, Spencer CW, J. Phys. Chem. Solids, 2, 240 (1957)

[6] Kaibe H, Sakata M, Isoda Y, Nishida I, J. Jpn. Inst. Met., 53, 958 (1989)

[7] Eklund PC, Mabatah AK, Rev. Sci. Instrum., 48, 775 (1977)

[8] Harman TC, Cahn JH, Logan MJ, J. Appl. Phys., 30, 1351 (1959)

[9] Goldsmid HJ, Proc. Phys. Soc., 71, 633 (1958)

[10] Goldsmid HJ, Thermoelectric Refrigeration, Plenum Press, New York, (1964).

[11] Seeger K, Semiconductor Physics, Springer-Verlag, New York, 61 (1982).

[12] Hyun DB, Hwang JS, Oh TS, Shim JD, Kolomoets NV, J. Phys. Chem. Solids, 59, 1039 (1998)

[13] Shockley W, Electrons and Holes in Semiconductor, Van Nostrand Co., (1950).

[14] Shigetomi S, Mori S, J. Phys. Soc. Jpn., 11, 915 (1956)

[15] loffe AF, Semiconductor Thermoelements and Thermoelectric Cooling, Infosearch, London (1957).

[16] Rowe DM, Bhandari CM, Modern Thermoelectrics, Holt, Rinehart and Winston, London, 22 (1983).

[17] Austin LG, Sheard A, J. electron. Contr., 3, 236 (1957)

[18] Greenaway DL, Harbake G, J. Phys. Chem. Solids, 26, 1585 (1965)