低维原子/分子晶体材料的可控生长、物性调控和原理性应用

本文介绍了高鸿钧课题组在物理所20年来的部分代表性工作.研究的主要方向为低维纳米功能材料的分子束外延可控制备、生长机制、物性调控及其在未来信息技术中的原理性应用.从材料的可控制备入手,结合第一性原理的理论计算,阐明材料生长机制和结构与物性的关系,进而实现物性调控和原理性应用.主要内容有:1)纳米尺度"海马"分形结构的形成及其生长机制;2)STM分辨率的提高及最高分辨Si(111)-7×7原子图像的获得;3)固体表面上功能分子的吸附、组装及其机制;4)稳定、重复、可逆的纳米尺度电导转变与超高密度信息存储;5)固体表面上单分子自旋态的量子调控及其原理性应用;6)原子尺度上朗德g因子的空间分辨及其空间分布不均匀性的发现;7)晶圆尺寸、高质量、单晶石墨烯的制备及原位硅插层绝缘化;8)几种新型二维原子晶体材料的可控构筑及其物性调控;9)"自然图案化"的新型二维原子晶体材料及其功能化.这些工作为低维量子结构的构造、物性调控及其原理性应用奠定了基础.

Construction,physical properties and applications of low-dimensional atomic/molecular crystals

In this article, we review the representative work that has been done by Hong-Jun Gao's group in the past two decades in Institute of Physics, Chinese Academy of Sciences. The work focuses on the construction, properties and applications of low-dimensional atomic/molecular crystals, covering the following 3 aspects.1) Construction and growth mechanisms of low-dimensional quantum structures. Firstly, we demonstrate the fabrication and growth mechanism of a seahorse shaped fractal pattern in C₆₀-TCNQ multilayer thin films by using the ionized-cluster-beam method. Secondly, by modifying the tip of the scanning tunneling microscope (STM), we clearly resolve the six rest atoms and twelve adatoms on a Si(111)-7×7 unit cell, showing the “highest-resolution” STM images of the Si(111)-7×7 surface. According to this work, we investigate the adsorption and bonding of Ge atoms on Si(111)-7×7 at low coverages. The configurations and growth behaviors of iron phthalocyanine molecules on Au(111) surface from sub-monolayer to bilayer are also reviewed. Furthermore, we demonstrate that organic molecules bond preferentially to different facets of the Ag(775) substrate under different deposition sequences, molecular lengths, terrace widths, and step heights. This can contribute to the design of non-templated selective functionalization of nanocrystals.2) Reversible conductance transition and spin on-off in low-dimensional quantum structures and applications in ultrahigh-density information storage. Firstly, we implement reversible, erasable, and rewritable nano-recordings on molecular thin films as a result of conductance transition. Then we demonstrate that the Kondo resonance of iron phthalocyanine molecules on an Au(111) substrate depends strongly on adsorption configuration, and the Kondo resonance of manganese phthalocyanine molecules can reversibly switch ON and OFF via attachment and detachment of single hydrogen atom to the molecule. Moreover, we achieve the site-dependent g factor of a single magnetic molecule with sub-molecular resolution, which shows an inhomogeneous distribution of the g factor within a single molecule. These results open up new routes to realizing ultrahigh-density information storage and controlling local spin properties within a single molecule.3) Construction, physical properties and applications of graphene and other two-dimensional atomic crystals. We start with the fabrication of a wafer-size, high-quality (almost defect free), single-crystalline graphene on Ru(0001). Then we demonstrate the structure of novel two-dimensional (2D) atomic crystals of mono-element, such as silicene,germanene, hafnene, and antimonene. Last but not least, we present the formation of intrinsically patterned bi-elements 2D materials, PtSe2 and CuSe, which can serve as templates for selective self-assembly of molecules and nanoclusters, as well as dual functionalization for catalysis or other applications.The series of work done in Hong-Jun Gao's group has laid a solid foundation in the research field of low-dimensional quantum structures and their applications.