非简谐振动对半导体基外延石墨烯热电效应变化规律的影响
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国家自然科学基金


Effects of non-harmonic vibration on the thermoelectric properties of semiconductor-based epitaxial graphene
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    摘要:

    本文建立了半导体基外延石墨烯的物理模型,考虑原子的非简谐振动,研究了它的杂化势以及热电势随化学势和温度的变化规律,探讨了原子非简谐振动对热电效应的影响. 对硅基外延石墨烯热电势的研究结果表明:简谐近似下,杂化势与温度无关;只考虑到第一非简谐项,杂化势随温度升高而增大;同时考虑到第一、第二非简谐项,则杂化势随温度升高而减小. 在给定温度下,外延石墨烯的热电势随化学势的变化在化学势为 处不具左右对称性,且在化学势为 eV附近有突变;给定化学势时,外延石墨烯热电势与单层石墨烯相似,均随温度升高而非线性减小,但外延石墨烯的值大于单层石墨烯的值;与简谐近似相比,非简谐效应会减小外延石墨烯热电势的值但减小量很小. 非简谐效应对热电势的影响随温度的升高而缓慢增大,大小在0.23%~0.25%之间.

    Abstract:

    In this paper, we establish the physical model of semiconductor-based epitaxial graphene. By considering the atomic non-harmonic vibration, we have the variations of the hybrid potential and thermoelectric potential of semiconductor-based epitaxial graphene with chemical potential and temperature are investigated, respectively. The influence of atomic non-harmonic vibration on the thermoelectric effect is also discussed. The results show that: 1) The hybrid potential is independent of temperature under the simple harmonic approximation. If the first non-harmonic term is considered, the hybrid potential increases with increasing temperature. However, if both the first and second non-harmonic terms are considered, the hybrid potential decreases with increasing temperature. 2) At a given temperature, the variation curve of thermoelectric potential of epitaxial graphene with chemical potential is left-right asymmetric at the chemical potential of zero, and there is a mutation near the chemical potential eV. 3) At a given chemical potential, the thermoelectric potential of epitaxial graphene is similar to that of single-layer graphene, namely that both decrease nonlinearly with increasing temperature, while the thermoelectric potential value of epitaxial graphene is larger than that of single-layer graphene. Compared with the simple harmonic approximation, the non-harmonic effect can reduce the thermoelectric potential value of the epitaxial graphene with a small amount. The influence of the non-harmonic effect on the thermoelectric potential increases slowly with increasing temperature, ranging from 0.23% to 0.25%.

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引用本文格式: 高君华,郑瑞伦. 非简谐振动对半导体基外延石墨烯热电效应变化规律的影响 [J]. 四川大学学报: 自然科学版, 2020, 57: 1157~1164.

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  • 收稿日期:2019-12-03
  • 最后修改日期:2020-01-10
  • 录用日期:2020-02-12
  • 在线发布日期: 2020-12-02