First-Principles Study Of Multilayer Material Of Two-Dimensional Boron Phosphide

The nanomaterials are those geometry size between1nm and100nm at less than one dimension, if this geometry size scale is at one dimention, the material names two-dimensional nanomaterial; if this geometry size scale at two dimensions, the material names one-dimensional nanomaterial; if this geometry size scale at three dimensions, the material names zero-dimensional material. In those nanomaterials, there are new special properties and quantum effects that can not be found in bulk systems, which deepens human being’s understanding of the nature world, and widely open up the application areas. The nanomaterials can be used in a variety of fields, including semiconductor, magnetic material, catalytic, computer, and medical applications and so on. The nanotechnology based on nanomaterials has been a important impact on today’s social progress and economic development, and has more and more effect with the time and may penetrate into people’s life in all aspects in future. Thus the nanomaterial has important research value.Since the graphene was isolated in2004, the2D material become research hot spot, including the Ⅳ elements such as silicene, germanane, and graphene itself, the Ⅲ-Ⅴ compounds such as h-BN, the V elements such as black phosphorus, and transition metal dichaldogenides (TMDCs) such as MoS2, as candidate materials for future optoelectronics and electronics applications. Recently, another2D material, boron phosphide (BP), attracts people’s attentions. Although this material has not been synthesized in experiment,.the BP film has been grew on the silicon surface recently, and there are some theoretical researchs for the stability and applications of low-dimensional BP. According to our studies, the2D BP has so excellent chemical and physical comprehensive properties that it can be widely used in semiconductor devices.For the reseach of nanomaterials, calculations based on first-principles density functional thory have become a very important tool. In this paper, we study a series of physical and chemical properties for2D BP.In the first chapter, we simply introduce the start and development of density functional theory within the first principles. In density functional theory, the basic quantity is the electron density instead of wavefunction in research, and the physical quantities are all treated as the function of electron density. Because electron density has only three dimensions, there is a large convenient both in concept and practical applications. In another way, the electron density as basic quantity can greatly reduce the amount of calculation and save the computing resources in practice. The density functional theory has some developments in many areas with partial success, especially for various kinds of ground state of materials, there is a big success. Finally, we introduce several common computing software packages related to density functional theory.In the second chapter, we first match the computed atomic and electronic structures of bulk BP with corresponding experimental data to determine the computation method. Then we give the structural information of monolayer BP, and discuss the possibility of the number of layers for2D BP when stripped from bulk BP. Moreover, the electronic structures of2D BP systems are calculated. Based on the character of band structures, we study the transport and optical properties. At last, we study the chemical stability and inertness in atmosphere environment for2D BP systems. According to our computations, the2D BP systems have excellent comprehensive properties in semiconductor devices which the other2D materials do not have, so2D BP systems have a wide application prospects.