The Study Of Atomic Layer Deposition Process And Mechanism Of Oxide Thin Films

Nanoscale iron oxide thin film is a photoelectric material with great development potential, which has advantages of good chemical durability, abundant storage and lower cost. And it has a broad application prospect in the field of catalysis, battery, sensor, magnetic recording and so on. With the development and application of the Fe₂O₃ thin film, the controlled synthesis should meet higher demands. Furthermore, as an advanced method to prepare thin film, the thin film prepared by atomic layer deposition is of a good character of shape-preserving, and an excellent property of controlling the deposition thickness in atomic scale.In the thesis, it was under the background of the study on the preparation of high quality iron oxide nano film with controllable shell thickness and in the method of atomic layer deposition, some contrast experiments of different depositional models, different surface states of substrate and cycle-indexes were conducted, the microstructure, surface state and chemical composition of thin film were characterized by means of SEM?Scanning Electron Microscope?, AFM?Atomic Force Microscope?, SE?Spectroscopic Ellipsometry?, XPS?X-Ray Photoelectron Spectroscopy?, XRD?X-Ray Diffraction? and so on, the effect of different technological parameters on preparation of iron oxide thin film by atomic layer deposition was explored, and the micro-growth mechanism of thin film was studied through film characterization results. On the basis, in the thesis, it was starting with elementary reaction, and the mechanism of atomic layer deposition of iron oxide thin film was described on a molecular level.In the thesis, there were two deposit models of Flow model and Stopover model, the deposition cycles of different cycle-indexes of 500, 1000, 2000, 3350, 4000 on OH basal deposit, H basal deposit and regular cleaning basal deposit were conducted individually with ferrocene and ozone molecules as precursors. It is showed that the deposition of Fe₂O₃ thin film was really realized through the deposit models designed in the thesis, and iron species were existed mainly in trivalent state, also divalent state and zero valent state in the component of the thin film. As to the two deposit models, it is found that the thin film grows on Flow model is of better uniformity but lower deposition rate?deposit rate at 0.138 ?/cycle? and poor efficiency than Stopover model. The efficiency of thin film prepared by Stopover model?deposit rate at 0.882 ?/cycle? is higher than that literature reports, but it is difficult to realize a thin film of good uniformity for it is of great roughness. In addition, OH basal deposit silica slice reflects a better absorption than H basal deposit and regular cleaning basal deposit for its nucleophilic catalysis, so Fe₂O₃ thin film grew on it has a bigger particle bulk in the situation of less cycle index and shorter deposition time?Flow model?. Fe₂O₃ thin film growth follows the typical Stranski-Krastanovs mode including three steps of nucleation, particles formation and thickening, which has a better guiding significance to research of technological parameter.In the thesis, the atomic layer deposition mechanism of Fe₂O₃ thin film was described on a molecular level by the data of quantum chemical calculation, the reaction between ferrocene molecules and ozone molecules on the surface of silicon slice that OH terminated was simulated, and the atomic layer deposition mechanism of Fe₂O₃ thin film was studied by Density Functional Theory. It is showed that the growth rate of thin film is restricted because of the restriction to reaction of adsorption site and the formation vacancy. The restriction to reaction of adsorption site is the main reason lead to a lower growth rate. And because the reaction is accompanied by the formation of vacancy, the Fe₂O₃ thin film prepared by the atomic layer deposition will be of great roughness.