Preparation Of Ir Coatings By MOCVD

In this thesis, the preparation of Ir coatings by MOCVD was investigated. The process, structure and the components were studied.The system of MOCVD was designed, assembled and debugged. Mo substrate was heated in a cold-wall MOCVD reactor in order to heat it more centrally; the rolling setting was used to deposit uniform coatings; the shape of reactor is connected with horizontal and vertical shape in order to place the source and rolling setting steadily. It simulated the conditions of the preparation of Ir coatings by MOCVD by Installation for the data record of dependence of the slight loss of weight on times. It can measured the sublimation rate of Ir(acac)3 uninterrupted.It was studied about the sublimation of the source that the sublimation rate increased with the rise of the temperature. The relationship between the sublimation rate and the substrate temperature accorded with Arrhenius form. The initial temperature of the source of Ir(acac)3 is choosed as 200℃ approximately that rise 5℃ with an interval of 10 miniutes.It was found during the preparation of Ir coatings by MOCVD that the depositing rate increased with the rise of the temperature. The relationship between the deposition rate and the substrate temperature accorded with Arrhenius form from 500℃ to 660 ℃. The value of the activation energy equals 56KJ/mol. High purity Ir coatings were obtained when a little oxygen was codosed. With the decreasing of the degree of vacuum, the purity of Ir coatings decreased. The particles of Ir coatings easily reunited with the rising of the temperature. The deposition rate of different places is mainly infected by the concentration distribution. With the closer distance of the entrance of gas, the deposition rate is higher. Finally the feasible factors are concluded that the temperature is 570, the degree of vacuum is 200 Pa approximately, the flow rate of oxygen is 20ml/min , and the flow rate of argon is steadily 0.21/min.The analysis of structure and components showed that the purity of the surface of Ir coatings is lower than the purity of the inside by XPS, the crystal phase in the coatings corresponds to the face-centered lattice of metal iridium., the size of the Ir crystallites was from 39 to 48 nm by XRD, and it indicated the isolated growth mechanism .