Electronic Conduction Channels Engineered in Topological Insulator Sputtered Thin Films
Electronic Conduction Channels Engineered in Topological Insulator Sputtered Thin Films
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DOI：
10.1021/acsaelm.2c00966
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发表时间：
2022-12
影响因子：
4.7
通讯作者：
S. Ferreira-Teixeira;A. Vanstone;A. Pires;W. Branford;J. P. Araújo;L. Cohen;A. Pereira
中科院分区：
文献类型：
--
作者：
S. Ferreira-Teixeira;A. Vanstone;A. Pires;W. Branford;J. P. Araújo;L. Cohen;A. Pereira
Sb 2 Te 3是一种拓扑绝缘体（TI）材料，可用于从能量收集到自旋轨道电子学的广泛应用。本文研究了离子束溅射纳米晶Sb 2 Te 3薄膜的结构、电学和热输运性质。厚度在35和300 nm之间的膜，具有尺寸为10-20 nm的纳米晶体，在300 K下具有0.072和2.03 Ω cm之间的高电阻率，随着冷却而增加。的塞贝克系数表明的n型和p型导电共存，后者在高温和较厚的膜更突出。的形态和传输特性表明，该膜是由两个层具有不同的多数电荷载流子，与电子体导电被描述的两个半导体层平行进行，一个p型在表面和另一个n型，每个描述的活化能依赖的导电性。除了这些散装的贡献，弱反局域化（WAL）尖点观察到低于10 K和低磁场下的磁导率。的WAL的分析提示，有一个二维的导电通道在低温下打开的较薄的膜，而对于较厚的膜，这种2D的传导似乎被掩盖的散装通道。然而，在2K下，观察到所有薄膜的磁局域化长度L Φ在62和90 nm之间。这种行为表明，随着体激活能传导在低温下冻结，电导由假定的2D状态进行，其似乎具有TI表面状态的一些特征。通过这些测量，我们表明，主导导电的类型可以控制在这些大面积溅射薄膜的Sb 2 Te 3膜厚度，而在低温下的传导似乎是由一个强大的TI状态为主。
Sb2Te3is a topological insulator (TI) material that can be used in a wide range of applications from energy harvesting to Spin-Orbitronics. In this paper, the structural, electrical, and thermal transport properties of nanocrystalline ion beam sputtered Sb2Te3thin films were studied. Films with thicknesses between 35 and 300 nm, with nanocrystallites of sizes 10–20 nm, have a high resistivity between 0.072 and 2.03 Ω cm at 300 K, increasing with cooling. The Seebeck coefficient demonstrates the coexistence of n-type and p-type conduction, the latter being more prominent at high temperatures and in thicker films. The morphological and transport properties reveal that the films are constituted by two layers having different majority charge carriers, with the electronic bulk conduction being described by two semiconductor layers conducting in parallel, one p-type at the surface and another n-type, each described by an activation energy-dependent conductivity. Besides these bulk contributions, weak antilocalization (WAL) cusps are observed in the magnetoconductance below 10 K and at low magnetic fields. Analysis of the WAL hints that there is one two-dimensional conduction channel open at low temperatures for the thinner films, whereas for the thicker film, this 2D conduction appears to be masked by the bulk channels. However, a magnetic localization lengthLΦbetween 62 and 90 nm at 2 K is observed for all thin films. This behavior suggests that as the bulk activation energy conductions freeze out at low temperatures, the electrical conduction is carried by the supposed 2D state, which appears to have some of the features of a TI surface state. Through these measurements, we demonstrate that the type of dominant conduction can be controlled by the Sb2Te3film thickness in these large area sputtered films, while the conduction at low temperatures appears to be dominated by a robust TI state.