First-Principles Study On Epitaxial Growth Of Two-Dimensional Black Phosphorus Materials

Semiconductor is a class of materials with conductive properties between conductors and insulators at normal temperature.It has important applications in integrated circuits,communication systems,photovoltaic power generation,high-power power conversion and other fields.With the progress of science and technology and the improvement of people’s living standard,these industries have put forward higher requirements for the performance of semiconductor devices.Research on new semiconductor materials is progressing rapidly.Among them,two-dimensional semiconductor materials due to their excellent performance have attracted wide attention,such as molybdenum disulfide（Mo S₂）,hexagonal boron nitride（h-BN）,etc.,which have been tapped out of the high potential and applied in a variety of electronic equipment,automobile and other manufacturing and medical industry.In recent years,two-dimensional Black phosphorus（Black P）has become a research hotspot due to its adjustable band gap and high carrier mobility.It is considered as a new material with great application potential.However,due to the difficulty in preparing high-quality black phosphorus bulk,only small areas of single crystal materials can be peeled off by top-down methods such as simple stripping,which greatly limits its further research and application.Bottom-up synthesis methods are now widely used to prepare large areas of high-quality two-dimensional materials such as graphene.Molecular beam epitaxy（MBE）is an ideal method for preparing single-layer or few-layer materials with the same growth source as the target materials.The core principle of MBE method is using growth substrate to regulate the dynamic process of material growth.MBE is a feasible method to prepare two-dimensional black phosphorus in large area.The key of black phosphorus growth is to find a substrate with moderate interaction.Therefore,it is particularly important to explore the growth mechanism of two-dimensional black phosphorus on various substrates and find a substrate suitable for low-cost and large-scale growth of two-dimensional black phosphorus.Compared with traditional experiments,theoretical calculation simulation based on first principles has the advantages of high efficiency,reliability,speed and low cost,which is the good choice for prospective exploration of experiments.This thesis studies the adsorption behavior and growth mechanism of two-dimensional black phosphorus on semiconductor substrate through first-principles calculation,which mainly includes the following two parts:1.Two-dimensional black phosphorus growth on ZnO（110）,GaN（110）,BP（110）,Si C（110）surfaces of bulk substrates.Based on density functional theory,the adsorption of single layer black phosphorus on the surface of four kinds of black phosphorus substrate and the initial growth behavior of black phosphorus were studied.The results show that ZnO（110）surface can stabilize the two-dimensional structure of monolayer black phosphorus,which is a potential excellent substrate for the growth of two-dimensional black phosphorus.Therefore,we further systematically studied the atomic diffusion properties of phosphorus on ZnO（110）surface,the stability of black phosphorus clusters and the stability of molecular dynamics simulation at different temperatures.The results show that the diffusion energy barrier of ZnO（110）surface P dimer is lower and the diffusion is faster than that of the P monomer.The structure of black phosphorus cluster is stable with the increase of phosphorus number,and the black phosphorus cluster with 22 atoms is also stable at 300 K.And the molecular dynamics simulations in the 6ps of black phosphorus monolayer showed the remarkable stability at 300 K and 500 K.In addition,our adsorption tests on the black phosphorus clusters on the surface of ZnO（110）steps show that the formation energy of the steps is larger and has more energy advantages than that on the plane.At the same time,the adsorption behavior of phosphorus atoms on GaN（110）,BP（110）and Si C（110）substrates was also studied.The results show that the formation of zigzag atomic chains on these three substrates is better than the two-dimensional layered structure.In addition,in the presence of half zigzag P chains,the single layer of black phosphorus on the three substrates can maintain a stable structure after relaxation.2.Growth of two-dimensional black phosphorus on SnSe（001）,GeSe（001）,Ge S（001）and Sb N（001）substrates.The adsorption of single layer black phosphorus on four substrates and the initial growth behavior of black phosphorus were studied by first principles calculation.The results show that the heterojunction structure of monolayer and bilayer substrates and monolayer black phosphorus is stable,but the structure of monolayer substrates is damaged and the phosphorus double bodies do not adsorb during the initial growth process.Therefore,the above two-dimensional black phosphorus substrates are not suitable for direct epitaxial growth of black phosphorus.