Preparation And Optical Properties Of Carbon Nutride Films

Carbon nitride films have attracted a lot of attention around the world for their excellent properties which are similar to DLC (Diamond Like Carbon) films. Such as, high degree of hardness, good friction and wear properties, liquid impact resistance, low electron affinity, chemical stability, et al. For many years, the researching work were mainly focusing on their preparation and mechanical properties. Recently, the electronic properties and cold cathode emission properties of CNx films attracted new attention. But few report about optical properties of CNx films were obtained.In this thesis, crystal structure, energy bond structure, mechanical, electronic properties and preparation methods of Carbon nitride films were introduced. The principle and characters of magnetron sputtering were discussed. Carbon nitride films with different nitrogen content were obtained by changing the sputtering power. The structure, optical properties, morphology and thermostabilization of carbon nitride films were investigated.The AFM images show that all the CN_X films have smooth surfaces. With sputtering power increasing, the surface roughness of CN_X films increase from 1.19nm to 2.28nm. that is better than α -C films (degree of roughness is 3.79nm). DTA-TG analysis show that the CNx film has little change in air from room temperature to 1000℃, the thermostabilization of CN_x is better than α -C films. X-ray diffraction measurements of the films showed that the CN_X films were amorphous (α -CN_X) because distinct diffraction peaks were not observed from all films. Composition of these films were obtained by XPS, N1s and C1s core energy spectra show that there are N-sp3 C and N-sp2 C bonds exist in these films. The ratio of N/C increases with the decrease of sputtering power, the ratio of N/C reach 0.5 at 276W. Raman spectra shows that the strength of I_d/I_g decreases with the sputtering power increase. UV/VIS spectrometer measured the transmittance of CN_X films. The transmittances of all CN_x films were about 75%. With the ratio of N/C increases the optical gap of CNx films increase, and the transmittance area broaden from 620 nm (ratio 0.18) to 410 nm (ratio 0.5). Calculation shows that by changing the sputtering power CN_x films with different optical band gap were obtained, for the CN_x film of which ratio of N/C is 0.5 the optical band gap reached 2.3eV.These results show that the film quality becomes better with the decrease of sputtering power. The excellent thermostabilization and the special optical properties made CNx film a good candidate for optical protective, reflection reducing, thermal conductive coating in photoelectronic devices and equipments.