Exploring Study of Novel Properties in Artificially Stacked Materials Grown by van der Waals Epitaxy

该项目旨在创造由高度非均质层制成的新型人工堆叠材料，并探索它们所表现出的新特性。通过扩展我们发展的范德华外延的思想，我们成功地生长出了各种异质结构。悬空键终止的概念使得在GaAs和Si等普通三维材料上生长许多层状材料成为可能。富勒烯和许多有机分子材料的良好外延薄膜也已成功制备。利用静电相互作用在晶格不匹配的碱卤化物或极性有机材料之间成功地在碱卤化物上进行异质外延，也增加了材料异质外延组合的可能性。本项目发现和研究的新性质包括STM图像的莫尔型调制，超薄膜中多型和电荷密度态的形成，通过堆叠控制酞菁薄膜的光学性质以及碱卤化物超薄外延膜中表面极化子色散的异常。通过蒙特卡罗研究、波段计算、量子蒙特卡罗分析等方法，对人工堆叠结构中的晶体生长、晶体结构、电子性能、超导介电性能等进行了理论研究。在一类由载流子带与侮辱带相互作用组成的排斥相互作用的电子系统中，证明了非迟滞吸引引起的超导性的发生。

This project has been fulfillled to create new artificially stacked materials made of highly heterogeneous layrs and to explore novel properties they show. By extending the idea of van der Waals epitaxy developed by us we have succeeded to grow various kinds of heterostructures. The concept of dangling bond termination has made it possible to grow many layred materials on such ordinary three-dimensional materials as GaAs and Si. Good epitaxial films of fullerene and many organic molecular meterials have also been fabricated successfully. Success in heteroepitaxy between lattice-mismatched alkali halides or polar organic materials on alkali halide by using electrostatic interaction has also increased the possible combination of materials in heteroepitaxy. New properties found and investigated in the present project include moiree-type modulation in STM image, polytype and charge density state formations in ultrathin films, control of optical properties of phthalocyanien films by stacking and anomaly in surface polariton dispersion in ultrathin epitaxial films of alkali halides. Crystal growth, crystal structure, electronic properties, superconductivity dielectric properties in the artificially stacked structures have been investigated theoretically by means of Monte Carlo study, Band, calculation, Quantum Monte Carlo study of analytical method. The occurrence of superconductivity due to nonretarded attraction has been demonstrated in a class of repulsively interacting electron systems that consist of a carrier band interacting with an insulting band.