【摘要】：表面原子吸附是改變半導體材料物理和化學性質(zhì)的最有效的方法之一。將金屬或非金屬原子吸附到單層黑磷(磷烯“phosphorene”)材料的表面,可以引起磷烯的能帶結構、電子態(tài)密度等電子結構和光學性質(zhì)的改變。經(jīng)過表面原子吸附處理的磷烯材料可以具有不同于本征磷烯的新特性,尤其是導電性和磁性的改變�；诹孔恿W和密度泛函理論的第一性原理的計算方法,是研究材料表面原子吸附的性能和微觀結構變化的一種比較有效的方法。利用第一性原理的計算方法進行表面吸附研究,不但可以詳細而又深入的了解磷烯材料的微觀幾何結構和其電子結構,從理論上驗證一些實驗現(xiàn)象的正確性和精確性,還可以探究材料的一些未知的特性,進而推進新材料的研發(fā)。本論文的研究工作主要分為以下幾個部分:第一部分研究了本征磷烯(phosphorene)的原子結構、電子結構和磁性。單層黑磷的結構為正交結構,它的空間群為Cmca(No.64),是一種典型的直接帶隙二維半導體材料。本文具體對其能帶結構和電子態(tài)密度進行了詳細的理論分析。計算結果驗證了實驗所得的磷烯所具有的物理特性的正確性。第二部分研究了磷烯表面吸附C、N、O、Na、Mg、Al原子的基本物理特性,包括最穩(wěn)定吸附位置、體系的幾何結構和電荷轉移情況等,并對計算結果進行了系統(tǒng)的分析。磷烯與金屬原子以及非金屬原子之間的相互作用都比較強,吸附能也比較大。磷烯表面吸附非金屬原子時,磷烯的P原子與非金屬原子形成了作用力比較強的共價鍵。吸附金屬原子時,其結合能比石墨烯的結合能要大得多,結構更加穩(wěn)定。電子由金屬原子轉移到了磷烯表面,這在磷烯作為電池電極材料方面有積極的作用。最后分析了磷烯吸附不同的原子后,其體系的能帶結構的變化和電子態(tài)密度隨能量變化的規(guī)律。本文針對不同的吸附原子,計算得出了他們的能帶結構圖、總的態(tài)密度和分波態(tài)密度圖,分階段分析了磷烯體系態(tài)密度的來源。根據(jù)計算,吸附N、Na、Al原子時,磷烯材料由直接帶隙性質(zhì)的半導體轉化成了導體。吸附C原子時,其體系比較特殊,由于自旋磁性的影響,材料的能帶結構分為上下自旋能帶,材料的性質(zhì)仍為半導體。吸附Mg原子時,體系保持半導體特性,帶隙比本征態(tài)時的帶隙要小。由于Mg原子的加入,體系由直接帶隙半導體轉變?yōu)榱碎g接帶隙的半導體。吸附O原子時,體系同樣保持半導體特性,O原子對體系能帶以及態(tài)密度的影響很小,其能帶結構與本征態(tài)的磷烯最為相似。通過對磷烯體系的系統(tǒng)分析,我們發(fā)現(xiàn)原子吸附影響磷烯特性發(fā)生改變的主要原因是不同原子間的相互作用和各不相同的電子轉移情況。這些理論結論可以為磷烯的更深層次的研究提供有效的數(shù)據(jù)。
[Abstract]:Surface atomic adsorption is one of the most effective methods to change the physical and chemical properties of semiconductor materials. The adsorption of metal or nonmetallic atoms onto the surface of monolayer black phosphorus ("phosphorene") materials can result in the changes of the electronic structure and optical properties of phosphonene, such as the energy band structure, electronic density of states and so on. The Phosphorene materials treated by surface atomic adsorption can have new properties different from those of intrinsic phosphorene, especially the changes of electrical conductivity and magnetic properties. The first-principle calculation method based on quantum mechanics and density functional theory is an effective method to study the properties and microstructure of atomic adsorption on the surface of materials. The study of surface adsorption by first-principle calculation method can not only understand the microstructure and electronic structure of phosphoenes in detail, but also verify the correctness and accuracy of some experimental phenomena in theory. We can also explore some unknown properties of materials, and then promote the development of new materials. The work of this thesis is divided into the following parts: in the first part, the atomic structure, electronic structure and magnetic properties of (phosphorene) are studied. The structure of monolayer black phosphorus is orthogonal, and its space group is Cmca (No.64), which is a typical direct band-gap two-dimensional semiconductor material. In this paper, the band structure and electron density of states are analyzed in detail. The calculated results verify the correctness of the physical properties of the experimental phosphorene. In the second part, the basic physical properties of the surface adsorption of C _ (N) N _ (N) O _ (O) Na _ (2) MgO _ (Al) atom on the surface of phosphorene are studied, including the most stable adsorption position, the geometric structure and the charge transfer of the system, and the calculated results are systematically analyzed. The interaction of phosphorene with metal and nonmetallic atoms is stronger and the adsorption energy is larger. When nonmetallic atoms are adsorbed on the surface of phosphorene, P atoms of phosphorene form covalent bonds with nonmetallic atoms. When metal atoms are adsorbed, its binding energy is much larger than that of graphene, and its structure is more stable. Electrons are transferred from metal atoms to the surface of phosphorene, which plays an active role in the use of phosphorene as electrode material for batteries. Finally, the changes of the energy band structure and the density of states of the system with different atoms adsorbed by phosphorene were analyzed. In this paper, the energy band structure diagram, the total density of states and the partial density of states are calculated for different adsorbed atoms, and the source of the density of states in the phosphorene system is analyzed in stages. According to the calculation, the phosphene material is transformed from a semiconductor with direct band gap to a conductor when it adsorbs the N _ (N) Na ~ (2 +) Al atom. When C atom is adsorbed, the system is special. Due to the effect of spin magnetism, the energy band structure of the material can be divided into upper and lower spin bands, and the properties of the material are still semiconductors. When Mg atoms are adsorbed, the band gap of the system is smaller than that of the intrinsic state. Because of the addition of Mg atom, the system changed from direct band gap semiconductor to indirect band gap semiconductor. When O atoms are adsorbed, the semiconductor properties of the system are also maintained. The influence of O atoms on the energy band and the density of states of the system is very small, and the band structure of the system is most similar to that of phosphorene in the intrinsic state. Through the systematic analysis of the phosphorene system, we find that the main reason for the influence of atomic adsorption on the properties of phosphorene is the interaction between different atoms and the different electron transfer. These conclusions can provide effective data for the deeper study of phosphorene.
【學位授予單位】：鄭州大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN304

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本文編號：2330147