Han Kyu-Bum, Chong Su Kong, Oliynyk Anton O, Nagaoka Akira, Petryk Suzanne, Scarpulla Michael A, Deshpande Vikram V, Sparks Taylor D
Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah, 84112, USA.
Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah, 84112, USA.
Sci Rep. 2018 Nov 23;8(1):17290. doi: 10.1038/s41598-018-35674-z.
Despite numerous studies on three-dimensional topological insulators (3D TIs), the controlled growth of high quality (bulk-insulating and high mobility) TIs remains a challenging subject. This study investigates the role of growth methods on the synthesis of single crystal stoichiometric BiSbTeSe (BSTS). Three types of BSTS samples are prepared using three different methods, namely melting growth (MG), Bridgman growth (BG) and two-step melting-Bridgman growth (MBG). Our results show that the crystal quality of the BSTS depend strongly on the growth method. Crystal structure and composition analyses suggest a better homogeneity and highly-ordered crystal structure in BSTS grown by MBG method. This correlates well to sample electrical transport properties, where a substantial improvement in surface mobility is observed in MBG BSTS devices. The enhancement in crystal quality and mobility allow the observation of well-developed quantum Hall effect at low magnetic field.
尽管对三维拓扑绝缘体（3D TIs）进行了大量研究，但高质量（体绝缘且高迁移率）拓扑绝缘体的可控生长仍是一个具有挑战性的课题。本研究调查了生长方法在单晶化学计量比BiSbTeSe（BSTS）合成中的作用。使用三种不同方法制备了三种类型的BSTS样品，即熔融生长（MG）、布里奇曼生长（BG）和两步熔融 - 布里奇曼生长（MBG）。我们的结果表明，BSTS的晶体质量强烈依赖于生长方法。晶体结构和成分分析表明，通过MBG方法生长的BSTS具有更好的均匀性和高度有序的晶体结构。这与样品的电输运性质密切相关，在MBG BSTS器件中观察到表面迁移率有显著提高。晶体质量和迁移率的提高使得在低磁场下能够观察到发育良好的量子霍尔效应。
