Journal of the Korean Vacuum Society (한국진공학회지)

The Korean Vacuum Society (한국진공학회)
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Thickness and Annealing Effects on the Thermoelectric Properties of N-type $Bi_2Te_{2.4}Se_{0.6}$ Thin Films

N형 $Bi_2Te_{2.4}Se_{0.6}$ 박막의 열전 특성에 미치는 두께 및 열처리 효과

  • Kim Il-Ho (Department of Materials Science and Engineering/ReSEM, Chungju National University) ;
  • Jang Kyung-Wook (Department of Materials Science and Engineering/ReSEM, Hanseo National University)
  • 김일호 (충주대학교 신소재공학과/친환경 에너지 변환 저장소재 및 부품개발 연구센터) ;
  • 장경욱 (한서대학교 신소재공학과/친환경 에너지 변환 저장소재 및 부품개발 연구센터)
  • Published : 2005.09.01
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Abstract

The effective mean free path model was adopted to examine the thickness effect on the thermoelectric properties of flash-evaporated n-type $Bi_2Te_{2.4}Se_{0.6}$ thin films. Annealing effects on the electron concentration and mobility were also studied, and their variations were analyzed in conjunction with antisite defects. Seebeck coefficient and electrical resistivity versus inverse thickness showed a linear relationship, and the mean free path was found to be $5120\AA$ Electron mobility was increased by annealing treatment and electron concentration was decreased considerably due to reduction of antisite defects, so that electrical conductivity was decreased and Seebeck coefficient was increased. When annealed at 473k for 1 hour, Seebeck coefficient and electrical conductivity were $-200\;\mu V/k\;and\;510\omega^{-1}cm^{-1}$, respectively. Therefore, the thermoelectric power factor was improved to be $20\times10^{-4}\;W/(mK^2)$.

순간 증착법으로 제조한 n형 $Bi_2Te_{2.4}Se_{0.6}$ 박막에 대하여 유효 평균 자유 행로 모델을 적용하여 박막의 두께가 열전 특성에 영향을 미치지 않는 임계 두께를 구하였다. 또한 열처리 전후 전자 농도 및 이동도의 변화를 조사하여 열처리에 의한 열전 특성의 변화를 역구조 결함과 관련하여 설명하였다. Seebeck 계수와 전기 비저항 모두 두레의 역수와 직선적인 관계를 보였으며, 이로부터 구한 평균 자유 행로는 $5120\AA$이었다. 열처리에 의해 전자의 이동도가 증가하였지만, 역구조 결함의 감소로 인해 운반자의 전자 농도가 현저히 감소하여, 결국 전기전도도가 감소하고 Seebeck 계수가 증가하였다 473k에서 1시간 동안 열처리한 Seebeck 계수와 전기전도도는 각각 $-200\;\mu V/k$와 $510\omega^{-1}cm^{-1}$이었다 또한, 열처리에 의해 열전 성능 인자가 상당히 향상되어 $20\times10^{-4}\;W/(mK^2)$를 나타내었다.

Keywords

References

  1. T. J. Seebeck, Abhandlugen der Deutschen Akademie der Wissershaften zu Berlin 265 (1822)
  2. J. C. A. Peltier, Ann. Chem. Phys. 56, 371 (1834)
  3. W. Thomson, Proc. Roy. Soc., 91 (1851)
  4. R. R Heikes and R. W. Ure, Jr., Thermoelectricity (Science andEngineering, Interscience Pub., New York-London, 1961), Chap. 1 and Chap. 3
  5. A. F. Ioffe, Semiconductor Thermoelements and Thermoelectric Cooling (Infosearch Ltd, London, 1957)
  6. E. Altenkirch, Phys. Z. 10, 560 (1909)
  7. H. J. Goldsmid, Thermoelectric Refrigeration (Plenum Press, New York, 1964), p. 42
  8. 上村欣一, 西田勳夫, 熱電半導體のその應用 (日刊工業新聞社, 東京, 1988), Chap. 1
  9. W. M. Yim and F. D. Rosi, Solid State Electronics 15, 1121 (1972) https://doi.org/10.1016/0038-1101(72)90172-4
  10. 西田勳夫, 熱發電素子の現狀 (自動車硏究 6, 1980), p. 79
  11. D. M. Rowe, Proc. 4th ICTEC, 96 (1982)
  12. N. Savides and H. J. Goldsmid, J. Mater. Sci. 15, 594 (1980) https://doi.org/10.1007/BF00551721
  13. N. G. Patel and P. G. Patel, Solid State Electronics 35, 1269 (1992) https://doi.org/10.1016/0038-1101(92)90160-E
  14. I. H. Kim and D. H. Lee, Proc. 12th ICT, 328 (1993)
  15. F. Volklein, V. Baier, V. Diller, and E. Kessler, Thin Solid Films 187, 253 (1990) https://doi.org/10.1016/0040-6090(90)90047-H
  16. L. Eckertova, Physics of Thin Film (Plenum Press, New York, 1986), p. 17
  17. Z. Stary, J. Horak, M. Stordeur, and M. Stolzer, J. Phys. Chem. Solids 48, 29 (1987) https://doi.org/10.1016/0022-3697(87)90138-7
  18. V. Damodara Das and N. Soundarajan, Phys. Rev. B37, 4552 (1988)
  19. I. H. Kim and K. W. Jang, J. Kor. Mater. Res. 14, 41 (2004) https://doi.org/10.3740/MRSK.2004.14.1.041