Transport Phenomena in Mixed Layered Tetradymite-like Compounds in the GeTe–Bi2Te3 System
Transport Phenomena in Mixed Layered Tetradymite-like Compounds in the GeTe–Bi2Te3 System
复制标题
GeTe-Bi2Te3 体系中混合层状辉辉石类化合物的输运现象
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
J. Fleurial
中科院分区：
文献类型：
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作者：
P. Konstantinov;L. E. Shelimova;E. S. Avilov;M. Kretova;J. Fleurial
GeBi[sub 2]Te[sub 4]-、Ge[sub 3]Bi[sub 2]Te[sub 6]-和GeBi[sub 4]Te[sub 7]-层状化合物的电传输特性被表征为温度的函数以及具有各种化学计量偏差的样品。霍尔系数和电阻率在 77 至 800 K 温度范围内测量，塞贝克系数在 90--450 K 温度范围内测定。在相当低的温度下，在这些三元化合物中观察到本征导电行为的开始。根据高温下电导率的变化，计算出 Ge[sub 3]Bi[sub 2]Te[sub 6]、GeBi[sub 2]Te[sub 4] 和 GeBi[sub 4]Te[sub 7] 化合物在 0 K 时的能隙值分别为 0.24、0.20 和 0.22 eV。为了解释载流子迁移率温度依赖性，提出了低温下声子和点缺陷的混合载流子散射机制。研究发现声声子散射的贡献随着温度的增加而增加。对GeBi[sub 4]Te[sub 7]化合物在150--200 K温度范围内的实验数据的分析表明需要额外的载流子散射机制，这可能与阳离子层中的有序-无序现象有关。对于化学计量的 GeBi[sub 2]Te[sub 4] 化合物，发现了霍尔系数的反常温度依赖性。这是由于 GeBi[sub 2]Te[sub 4] 晶体中成分波动以及 p 型和 n 型导电域的存在而产生的混合载流子传导效应来解释的。 « less
The electrical transport properties of the GeBi[sub 2]Te[sub 4]-, Ge[sub 3]Bi[sub 2]Te[sub 6]-, and GeBi[sub 4]Te[sub 7]-layered compounds were characterized as a function of temperature and for samples with various stoichiometric deviations. The Hall Coefficient and electrical resistivity were measured from 77 to 800 K, and the Seebeck coefficient was determined in the 90--450 K temperature range. The onset of intrinsic conductivity behavior was observed in these ternary compounds at fairly low temperatures. On the basis of the variation of the electrical conductivity at elevated temperatures, energy gap values of 0.24, 0.20, and 0.22 eV were calculated at 0 K for the Ge[sub 3]Bi[sub 2]Te[sub 6], GeBi[sub 2]Te[sub 4], and GeBi[sub 4]Te[sub 7] compounds, respectively. To explain the carrier mobility temperature dependence, a mixed carrier scattering mechanism on acoustic phonons and point defects is proposed at low temperatures. It is found that the contribution of scattering by acoustic phonons increased with temperature. The analysis of experimental data for the GeBi[sub 4]Te[sub 7] compound in the 150--200 K temperature range demonstrated the need for an additional carrier scattering mechanism, probably connected to the order-disorder phenomena in the cation layers. An anomalous temperature dependence of the Hall coefficient was discovered for themore » stoichiometric GeBi[sub 2]Te[sub 4] compound. It is explained by mixed carrier conduction effects due to fluctuations of the composition and the existence of p- and n-type conductivity domains in the GeBi[sub 2]Te[sub 4] crystal.« less