Low-temperature transport properties of TaxN thin films (0.72 ⩽ x ⩽ 0.83)
Low-temperature transport properties of TaxN thin films (0.72 ⩽ x ⩽ 0.83)
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DOI：
10.1088/0022-3727/43/44/445405
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发表时间：
2010-10
期刊：
影响因子：
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通讯作者：
M. Ocko;S. Zonja;Greg L. Nelson;J. Freericks;Lei Yu;N. Newman
中科院分区：
文献类型：
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作者：
M. Ocko;S. Zonja;Greg L. Nelson;J. Freericks;Lei Yu;N. Newman
我们报告了沉积在非晶 SiO2 基底上的 TaxN 薄膜的低温 (4–320 K) 传输特性。在这项工作中，TaxN 薄膜被限制在 x 的狭窄范围内：0.72 ≤ x ≤ 0.83，但其输运特性随 Ta 浓度的变化却表现出相当大的非单调变化。这种行为与费米能级电子态密度的局部最小值一致（根据岩盐金属间化合物 Ta4N5 的计算）以及用于描述输运的刚性能带模型。电阻率的温度依赖性最适合不寻常的形式 exp(−T/T0)。有趣的是，拟合参数 T0 与相应热电势最大值的温度密切相关。当化学势具有非平凡的温度依赖性时，这两个特征，即与热电势的拟合和相关性，都与电荷和热传输的 Jonson-Mahan 多体形式一致。在测量的最低温度下，我们还发现电阻率和热电势显示出电子-电子相互作用的特征。我们还根据一些通常用于描述薄膜传输的理论以及在 TaxN 上进行的其他实验研究来讨论我们的结果。
We report on low-temperature (4–320 K) transport properties of TaxN thin films deposited on an amorphous SiO2 substrate. In this work, TaxN thin films were restricted to a narrow range of x: 0.72 ⩽ x ⩽ 0.83 yet show considerable and nonmonotonic variation of their transport properties with Ta concentration. This behaviour is consistent with a local minimum in the density of electronic states at the Fermi level, as calculated for the rock salt intermetallic Ta4N5, and a rigid band model for describing the transport. The temperature dependence of the resistivity is best fit to the unusual form exp(−T/T0). Interestingly enough, the fit parameter T0 correlates well with the temperature of the maximum of the corresponding thermopower. Both of these characteristics, the fit and the correlation with the thermopower, are consistent with the Jonson–Mahan many-body formalism for charge and thermal transport when one has a nontrivial temperature dependence of the chemical potential. At the lowest temperatures measured, we have also found that the resistivity and thermopower show signatures of electron–electron interactions. We discuss also our results in the light of some theories usually used for describing transport of thin films and to other experimental investigations that have been performed on TaxN.