Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
권호 표지
DOI QR코드

DOI QR Code

The Effect of Stacking Fault on Thermoelectric Property for n-type SiC Semiconductor

N형 SiC 반도체의 열전 물성에 미치는 적층 결함의 영향

  • Pai, Chul-Hoon (Division of Bio-Engineering, Incheon National University)
  • 배철훈 (인천대학교 생명공학부)
  • Received : 2020.12.07
  • Accepted : 2021.03.05
  • Published : 2021.03.31
Download PDF
⟨ Previous Next ⟩

Abstract

This study examined the effects of stacking faults on the thermoelectric properties for n-type SiC semiconductors. Porous SiC semiconductors with 30~42 % porosity were fabricated by the heat treatment of pressed ��-SiC powder compacts at 1600~2100 ℃ for 20~120 min in an N2 atmosphere. XRD was performed to examine the stacking faults, lattice strain, and precise lattice parameters of the specimens. The porosity and surface area were analyzed, and SEM, TEM, and HRTEM were carried out to examine the microstructure. The electrical conductivity and the Seebeck coefficient were measured at 550~900 ℃ in an Ar atmosphere. The electrical conductivity increased with increasing heat treatment temperature and time, which might be due to an increase in carrier concentration and improvement in grain-to-grain connectivity. The Seebeck coefficients were negative due to nitrogen behaving as a donor, and their absolute values also increased with increasing heat treatment temperature and time. This might be due to a decrease in stacking fault density, i.e., a decrease in stacking fault density accompanied by grain growth and crystallite growth must have increased the phonon mean free path, enhancing the phonon-drag effect, leading to a larger Seebeck coefficient.

n형 SiC 반도체에서 적층 결함이 열전 물성에 미치는 영향에 대해 연구하였다. ��-SiC 분말 성형체를 질소 분위기에서 1600~2100 ℃, 20~120분간 열처리해서 30~42 %의 기공률을 갖는 다공질 SiC 반도체를 제작하였다. X선 회절 분석으로 적층 결함량, 격자 스트레인 및 격자 상수를 산출하였고, 미세 구조 분석을 위해서 기공률 및 비표면적 측정과 함께, 주사 전자현미경 (SEM), 투과 전자현미경 (TEM) 및 고분해능 전자현미경 (HREM) 등을 관찰하였다. Ar 분위기 550~900 ℃에서 도전율과 Seebeck 계수를 측정 및 산출하였다. 열처리 온도가 높을수록, 처리 시간이 길어질수록 캐리어 농도 증가 및 입자와 입자간의 연결성 향상에 의해 도전율이 향상되었다. 도너로 작용하는 질소의 고용으로 Seebeck 계수는 음(-)의 값을 나타내었고, 도전율과 마찬가지로 열처리 온도 및 시간이 상승함에 따라 Seebeck 계수의 절대 값이 증가하였다. 이는 적층 결함의 감소, 즉 입자 및 결정 성장과 함께 적층 결함 밀도의 감소에 의해 포논의 평균 자유 행정이 증가해서 결과적으로 포논-드랙 효과에 의한 Seebeck 계수의 향상으로 나타난 것으로 판단된다.

Keywords

References

  1. K. Uemura and I. Nishida, Thermoelectric Semiconductors and Their Applications, Nikkankogyoshinbunsha, 1988, pp.33-37.
  2. I. B. Cadoff and E. Miller, Thermoelectric Materials and Devices, Chapman and Hall Ltd., 1960, pp.178-183. DOI: https://dx.doi.org/10.1063/1.3057558
  3. K. Uemura and I. Nishida, Thermoelectric Semiconductors and Their Applications, Nikkankogyoshinbunsha, 1988, pp.1-7.
  4. K. Koumoto, C. H. Pai, S. Takeda, and H. Yanagida, "Microstructure-controlled Porous SiC Ceramics for High-temperature Thermoelectric Energy Conversion", Proc. of the 8th Inter. Conf. on Thermoelectric Energy Conversion, ECT, Nancy, France, pp.107-112, 1989.
  5. C. H. Pai, K. Koumoto, S. Takeda, and H. Yanagida, "Preparation of SiC Hollow Particles by Gas-Phase Reaction and Thermoelectric Properties of Sintered Bodies", Solid State Ionics, 32/33, pp.669-677, 1989. https://doi.org/10.1016/0167-2738(89)90343-3
  6. W. S. SEO, C. H. Pai, K. Koumoto, and H. Yanagida, "Microstructure Development and Stacking Fault Annihilation in β-SiC Powder Compact", J. Ceram. Soc. Jpn., 99[6], pp.443-447, 1991. DOI: https://dx.doi.org/10.2109/jcersj.99.443
  7. W.S. Seo, C.H. Pai, K. Koumoto, and H. Yanagida, "Effects of Additives on the Stacking Fault Annihilation in β-SiC Powder Compacts," J. Ceram. Soc. Jpn., 99[12] pp.1179-1184, 1991. DOI: https://doi.org/10.2109/jcersj.99.1179
  8. W.F. Knippenberg and G. Verspui, "The Influence of Impurities on the Growth of Silicon Carbide by Recrystallization," Mater. Res. Bull., 4 45-56 (1969). https://doi.org/10.1016/0025-5408(69)90015-4
  9. V. Munch, "Silicon Carbide," Landolt-Bornstein, 17 [a] 132-42 (1982).
  10. J. Y. W. Seto, "The Electrical Properties of Polycrystalline Silicon Films", J. Appl. Phys., 46[12], pp.5247-5254, 1975. DOI: https://dx.doi.org/10.1063/1.321593
  11. J. Y. M. Lee and I. C. Cheng, "Electrical Properties of Lightly Doped Polycrystalline Silicon", J. Appl. Phys., 53[1], pp.490-495, 1980. DOI: https://dx.doi.org/10.1063/1.329952
  12. J. E. Parrott, "Some Contributions to the Theory of Electrical Conductivity, Thermal Conductivity, and Thermoelectric Power in Semiconductors", Transport Phenomena in Semiconductors, B70, pp.590-607, 1957.