【作者】 刘志锋；

【导师】 祝恒江；

【作者基本信息】 新疆师范大学 ， 课程与教学论， 2011， 硕士

【摘要】 III-V族低维半导体材料,在纳米光电子学、集成电路和纳米器件等方面有着极为重要的作用。近几十年来,人们在III-V族半导体薄膜、超晶格、纳米管和量子点的实验及理论研究中取得了巨大的进步,但截止目前,对于III-V族砷化硼和砷化铟在1~200个原子范围内的研究却很有限。为此,文章采用密度泛函理论(DFT)对砷化硼以及砷化铟半导体团簇的几何结构、稳定性和电子性质进行了研究。首先,应用密度泛函理论的全电子方法优化得到了BnAsn (n=1-14)团簇基态几何结构,并对其稳定性和电子性质做了系统分析。结果表明,当n=4时团簇的基态由二维平面结构过渡到三维立体,当n > 4时团簇的基态随尺寸的增加而形成以B原子与As原子交替排列的四元环和六元环为结构基元的笼状构型;具有高对称的富勒笼状结构B12As12为最稳定团簇;能隙的取值范围显示BnAsn (n=1-14)团簇具有典型的半导体特征;BnAsn (n=1-14)团簇具有较强的分子特性和共价特性。其次,采用密度泛函理论下的赝势方法优化得到了五种稳定的InnAsn (n=4-90)管状团簇。通过研究发现,它们遵循着有趣的结构衍化规律,所有管状团簇在结构上都满足共同的分子通式Inpk/2As pk/2。管状团簇的主要结构单元是两个相互平行的p边形,外加p个四元环以及h个六元环结构,其中h、p和原子层数k满足关系:h=p×(k-2)/2。管状团簇的HOMO、LUMO的电子分布特征揭示了管状结构形成的内在原因,同时它也在微观层面上解释了实验中一维InAs纳米材料的生长机理。最后,以稳定管状团簇的结构为基础,通过搭建原胞,在周期边界条件下优化得到了无限长InAs纳米管的几何结构。结果表明,无限长纳米管具有与管状团簇极为类似的构型,且能带结构的分析发现不同类型的纳米管都表现出宽带隙的半导体特征。研究结果对于深入理解砷化硼团簇以及砷化铟纳米管的结构衍化和电子性质提供了一定的帮助,为III-V族低维半导体材料的进一步实验研究提供可靠的理论依据。更多还原

【Abstract】 Low-dimension semiconductor materials of the III-V group is playing an important role in the fields, such as nano-optical electronics, molectron and nanodevice . For the past decades, theoretic and experimental study about the film, superlattice, nanotube and quantum dot of the III-V group semiconductor have achieved a great progress. However, by now, the investigation of boron arsenide and indium arsenide in 1 to 200 scope of the number of atoms is still very limited. Therefor, in this paper a study of the geometric, stability and electronic properties of boron arsenide and indium arsenide clusters, have been carried by density functional theory (DFT).First of all, the investigation of the lowest-energy structures, stabilities and electronic properties of BnAsn clusters (n=1-14) have been presented by means of the density-functional theory. The results show that the lowest-energy structures undergo a structural change from two-dimensional to three-dimensional when n=4. With the increase of the cluster size (n>4), the BnAsn clusters tend to adopt cage-like structures, which can be considered as being built from four-membered rings (4MRs) and six-membered rings(6MRs). B12As12, a fullerene-like cage with high symmetry, is the most stable cluster. The results of PDOS analysis reveal that a distinct spd hybrid can be found at the vicinity of Fermi level, and there are strong molecular and covalent characteristic in the clusters.Moreover, the effective core potential density functional calculations are performed to explore a series of InnAsn tubelike clusters up to n=90. It is interesting that all of the tubelike structures comply with some common properties, such as the general molecular structural formula Inpk/2Aspk/2 and the common structure units—the parallel polygons, 4MRs and 6MRs. Size-dependent cluster properties such as binding energy, HOMO-LUMO gaps, Mulliken charges on atoms and frontier molecular orbital surfaces have been discussed. The electron density distributions of HOMO and LUMO indicate that the chemical activity of the tubelike clusters at the two ends is stronger, which makes the clusters being conducive to grow longer. That is why we can get the tube-like clusters.Finally, based on the stable tube-like cluster structures, the same method have been employed to optimize the infinite InAs nanotubes (InAsNTs). Their atomic and electronic band structures are presented. The results show that one-dimensional InAsNTs can be prepared by proper assembly of tubelike clusters to form semiconductors with large band gap.The results of these studies are helpful for us to understand the growth of the structures and electronic properties of the boron arsenide clusters and indium arsenide nanotubes. Furthermore, they can present theoretical credible basis for the further experimental study of the low-dimension semiconductor materials of the III-V group.更多还原