Preparation And Characterization Of Transitional Metal Chromium Oxynitride(CrO_xN_y)thin Films

Transition metal nitride and oxides have been studied extensively because of their excellent physical,chemical and mechanical properties.Transition metal NOx with ionic bond and covalent bond has excellent properties of both nitride and oxides.Transition metal oxide thin has good chemical stability,high refractive index and large bandwidth,and the performance mouldability can be realized by adjusting the change of composition proportion.Based on the superior properties of transition metal NOx mentioned above,this thesis intends to prepare Cr(NOx)films by reactive magnetron sputtering.Taking Cr compounds as the target material,different reaction gases are introduced to prepare Cr(NOx)films.The effects of process parameters on sample composition,band gap value,crystallization and electrical properties are studied.The main findings are as follows:(1)When taking chromium oxide as the target material,the first fixed power,by changing the atmosphere to prepare different components of chromium nitric oxide film.The XRD results show that the crystal phase of the prepared films is mainly Cr O2 phase,and the crystal growth along the Cr O2(110)plane is preferred;The elemental composition of the film was deduced from XPS results.The results showed that when the nitrogen flow rate was 3sccm,5sccm,and 8sccm,the content of oxygen and nitrogen in the sample did not change much,and the ratio of nitrogen to oxygen was basically unchanged,(O+N)/Cr was about 1.75.When the nitrogen flow rate is further increased,the nitrogen content gradually increases,and the N/O atomic ratio gradually increases.The results of XPS fitting indicated that the samples mainly contained Cr-N bonds corresponding to Cr N and Cr-O bonds corresponding to Cr O2 and Cr O3.The optical test results show that the transmittance increases gradually in the wavelength range of 300?500nm,and then becomes stable in the wavelength range of 500?1200nm,and the transmittance value is about 85%.The results of absorption test show that there is a low absorption in the visible region,and the obvious change of absorption value occurs in the wavelength of 200?380nm,and the band gap value ranges from 2.0?2.8e V.The electrical test results show that the square resistance of the sample decreases with the increase of nitrogen flow rate.However,when the nitrogen flow rate is from 8sccm to 10 sccm,the square resistance of the sample decreases obviously.(2)Taking chromium oxide as the target material,fixing the nitrogen flow rate,and changing the power to prepare different components of chromium nitric oxide films.The XRD results show that with the increase of power,the diffraction peak intensity of the film in the Cr O2(110)direction increases first and then decreases,and the crystallinity of the sample is the best at 120 W.When the power is 120 W,the nitrogen content is the highest.With the increase of nitrogen flow rate,the N/O ratio in the film increases gradually.The optical test results show that the transmittance increases gradually in the wavelength range of 200?400nm,and tends to be stable in the wavelength range of400?1200nm,and the transmittance value is about 78%.The absorption test results showed that there was a low absorption in the visible light region,and the absorption value significantly changed between 200 nm and 380 nm,and the band gap value ranged from 2.5e V to 2.9e V.The square resistance value of the film prepared with 120 W RF power is the smallest.(3)With chromium nitride as the target material and oxygen as the reaction gas,the nitrogen element in the prepared film is lost seriously.The main component is chromium oxide,and the maximum atomic percentage of Cr/O is about 1:1.8,which mainly exists in the form of Cr O2 phase structure.XPS results showed that when oxygen of 1sccm was added,N1 s in the sample disappeared,indicating that the sample was easily oxidized.According to the fitting of XPS fine spectrum,the main chemical bond in the sample was the Cr-O bond corresponding to the compound Cr O2.The optical test results show that the transmission value of the sample increases linearly with the wavelength,and the mean value in the tested wavelength range is more than 60%.The absorption changes occurred in the wavelength range of 200?350nm,and the band gap values measured by the films ranged from1.3?1.5e V.The electrical test results show that when the RF power is a constant value of120 W,the square resistance of Cr Ox Ny film increases slightly with the increase of oxygen flow.