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<p>The reported experimental data of the temperature dependence of the electrical conductivity, the Hall coefficient, and the Hall mobility below room temperature on undoped <i>n</i>-type samples of Mg<sub>2</sub>Si have been simultaneously fitted taking into account hopping conduction mechanisms. It is shown that the electron transport in the conduction band can be described within a parabolic band model assuming a density-of-state effective mass of <i>m</i><sub>dse</sub>&#xa0;=&#xa0;0.596 <i>m</i><sub>0</sub>, where <i>m</i><sub>0</sub> denotes the free electron mass, with scattering mechanisms due to ionized impurities, acoustic phonons, and polar optical phonon. In particular, the significant effect of polar optical phonons due to the large Fröhlich coupling constant is pointed out. In the samples with small concentrations of impurities, only nearest-neighbor hopping was observed in the measurement temperature range down to 10&#xa0;K, whereas the dominance of nearest-neighbor hopping is observed to be replaced by that of variable-rang hopping at low temperatures in the samples with higher concentrations of impurities. It is also shown that the prominent peak of the absolute value of the Seebeck coefficient observed around 20&#xa0;K in a sample can be attributed to nearest-neighbor hopping conduction, whereas it was attributed to the phonon-drag effect in a previous study.</p>

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Analyses of Electrical Transport Data on Undoped n-type Mg2Si Including Significant Effects of Polar-Optical-Phonon Scattering and Hopping Conduction

  • 期刊论文

  • 发表日期：

    2025年8月18日

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  • Yasutomo Kajikawa,
  • Naomi Hirayama

摘要

The reported experimental data of the temperature dependence of the electrical conductivity, the Hall coefficient, and the Hall mobility below room temperature on undoped n-type samples of Mg2Si have been simultaneously fitted taking into account hopping conduction mechanisms. It is shown that the electron transport in the conduction band can be described within a parabolic band model assuming a density-of-state effective mass of mdse = 0.596 m0, where m0 denotes the free electron mass, with scattering mechanisms due to ionized impurities, acoustic phonons, and polar optical phonon. In particular, the significant effect of polar optical phonons due to the large Fröhlich coupling constant is pointed out. In the samples with small concentrations of impurities, only nearest-neighbor hopping was observed in the measurement temperature range down to 10 K, whereas the dominance of nearest-neighbor hopping is observed to be replaced by that of variable-rang hopping at low temperatures in the samples with higher concentrations of impurities. It is also shown that the prominent peak of the absolute value of the Seebeck coefficient observed around 20 K in a sample can be attributed to nearest-neighbor hopping conduction, whereas it was attributed to the phonon-drag effect in a previous study.