Tuning the Band Structure of Silicene by Surface and Interface Control

该项目由材料研究部(DMR)的电子与光子材料(EPM)和固态与材料化学(SSMC)计划联合资助。非技术描述：在石墨烯中发现的奇异物理现象激发了人们对各种二维(2D)材料的巨大科学兴趣。只有一个或几个原子层厚度的2D材料在器件可伸缩性和摩尔定律的推广方面比块体材料更有利。本项目致力于硅烯的探索和能带结构的调整，这是一种以蜂窝模式排列的硅原子的单分子膜，具有适应主流硅基电子学和自旋电子学应用的潜力。教育部分包括在跨学科的学术环境中培训研究生，将研究与本科生教育和密歇根州立大学的本科生研究经验计划相结合，招收少数族裔学生，并通过在密歇根州立大学建立的科学剧院等外联活动向更广泛的受众传播研究。技术说明：硅烯是一种新兴的2D材料，有望展示像石墨烯一样的狄拉克物理，但具有更大的自旋-轨道耦合。到目前为止，大多数硅烯的生长都是在Ag(111)衬底上进行的，在二硼化锆和Ir衬底上生长的硅烯也取得了很小的成功。然而，与衬底的强相互作用使得分离硅烯和测量其电输运性质变得困难。该项目旨在解决这些关键问题：1)探索硅烯在氮化硼等绝缘衬底上的生长，以探索其内在性质；2)通过表面化学官能化来调节硅烯的带隙和载流子浓度。广泛而连续的能带结构调整对于探索硅烯的性质及其在开关器件中的潜在应用具有重要意义。采用扫描隧道显微镜/光谱、非接触原子力显微镜、紫外光电子能谱和X射线光电子能谱等综合实验手段对硅烯的表面进行了表征，并测量了其电子结构。

The project is jointly funded by the Electronic and Photonic Materials (EPM) and the Solid State and Materials Chemistry (SSMC) Programs, both in the Division of Materials Research (DMR).Non-technical Description: The exotic physical phenomena discovered in graphene have spurred great scientific interest in various two-dimensional (2D) materials. 2D materials with only one or a few atomic layers in thickness are favorable over bulk materials in terms of device scalability and the extension of Moore's law. This project focuses on the exploration and band structure tuning of silicene, a monolayer of Si atoms arranged in a honeycomb pattern, which has the potential to be adapted to the mainstream silicon-based electronics and applications in spintronics. The educational component includes training graduate students in an interdisciplinary academic environment, integrating research with undergraduate education and with the Research Experience for Undergraduates program at Michigan State University, recruiting minority students, and disseminating research to an even broader audience through outreach activities such as Science Theatre that has been established at the University.Technical Description: Silicene is an emerging 2D material with the promise of exhibiting Dirac physics like graphene but of a larger spin-orbit coupling. To date most of the silicene growth has been carried out on Ag(111) substrate, with marginal success on zirconium diboride and iridium. However, the strong interaction with the substrate renders it difficult to isolate silicene and to measure its electrical transport properties. This project aims to address these critical issues by 1) exploring growth of silicene on insulating substrates such as boron nitride in order to probe its intrinsic properties; and 2) tuning the band gap and carrier concentration of silicene via surface chemical functionalization. A wide and continuous tuning of the band structure is important for exploring properties of silicene and its potential applications in switching devices. A comprehensive experimental approach including scanning tunneling microscopy/spectroscopy, non-contact atomic force microscopy, ultraviolet and x-ray photoelectron spectroscopy is taken to characterize the surface and to measure the electronic structures of silicene.