Tang Hao, Wang Xiaomeng, Xiong Yucheng, Zhao Yang, Zhang Yin, Zhang Yan, Yang Juekuan, Xu Dongyan
Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong Special Administrative Region.
Nanoscale. 2015 Apr 21;7(15):6683-90. doi: 10.1039/c5nr00917k.
Bismuth selenide (Bi2Se3) nanoribbons have attracted tremendous research interest recently to study the properties of topologically protected surface states that enable new opportunities to enhance the thermoelectric performance. However, the thermoelectric characterization of individual Bi2Se3 nanoribbons is rare due to the technological challenges in the measurements. One challenge is to ensure good contacts between the nanoribbon and electrodes in order to determine the thermal and electrical properties accurately. In this work, we report the thermoelectric characterization of individual Bi2Se3 nanoribbons via a suspended microdevice method. Through careful measurements, we have demonstrated that contact thermal resistance is negligible after the electron-beam-induced deposition (EBID) of platinum/carbon (Pt/C) composites at the contacts between the nanoribbon and electrodes. It is shown that the thermal conductivity of the Bi2Se3 nanoribbons is less than 50% of the bulk value over the whole measurement temperature range, which can be attributed to enhanced phonon boundary scattering. Our results indicate that intrinsic Bi2Se3 nanoribbons prepared in this work are highly doped n-type semiconductors, and therefore the Fermi level should be in the conduction band and no topological transport behavior can be observed in the intrinsic system.
近年来，硒化铋（Bi2Se3）纳米带因其拓扑保护表面态的特性而引发了大量研究兴趣，这些特性为提升热电性能带来了新机遇。然而，由于测量中的技术挑战，对单个Bi2Se3纳米带的热电特性研究较为罕见。其中一个挑战是确保纳米带与电极之间良好的接触，以便准确测定热学和电学性质。在这项工作中，我们报告了通过悬浮微器件方法对单个Bi2Se3纳米带进行的热电特性研究。通过仔细测量，我们证明了在纳米带与电极之间的接触处进行铂/碳（Pt/C）复合材料的电子束诱导沉积（EBID）后，接触热阻可忽略不计。结果表明，在整个测量温度范围内，Bi2Se3纳米带的热导率小于其体材料值的50%，这可归因于声子边界散射的增强。我们的结果表明，在这项工作中制备的本征Bi2Se3纳米带是高度掺杂的n型半导体，因此费米能级应处于导带中，且在本征体系中无法观察到拓扑输运行为。
