Preparation And Photoluminescence Of SiC Nanocrystal Films

In the thesis, the history of SiC material was briefly reviewed and basic properties, preparation and research survey of SiC material were summarized.The principle of sputtering technology and its application in SiC film preparation were introduced.The SiC nanocrystal films were prepared successfully on Si (111) substrates by rf magnetron sputtering and then annealed in a vacuum annealing system. The effects of technical parameters on film structure, composition and photoluminescence (PL) properties were studied by XRD, FTIR, SEM, XPS and PL. The results showed that different annealing temperature effect on the structure and PL. The PL peak shifts to short wavelength side and the PL intensity becomes stronger as the annealing temperature decreases. A higher bias can improve the film crystallization and constrain the formation of amorphous carbon and SiO2.The PL peak shifts to short wavelength side and the PL intensity becomes stronger as the bias pressure increases. Moreover, it was found that a higher RF power can improve the film crystallization and PL intensity. Finally, excessive working gas pressure will result in the decrease of the deposition rate for SiC thin film. The theory of PL decay was introduced detailedly, the time-resolved spectrum devices was introduced briefly. The luminescence origin of SiC nanocrystal films were studied by time-resolved spectrum. Time-resolved spectrum of the PL at the peak value energy exhibits a bi-exponential decay process with lifetimes of picoseconds and nanoseconds. It is at least two orders of magnitude faster than that of bound excitonic transitions in the bulk 3C-SiC at low temperatures. The strong light emission with short PL lifetimes suggests that the radiative recombination is a result of direct optical transitions due to quantum confinement effect of the SiC nanocrystallites.β-SiC films were prepared on silicon substrates by rf sputtering method. Porousβ-SiC films were fabricated by electrochemical anodization in the HF(40%)-ethanolic(99%) solution. The surface morphology and the structure were studied by SEM, FTIR, XPS. The luminescence mechanism of the porousβ-SiC films were discussed, intense blue luminescence was observed at room temperature. It was the PL peak of the porous SiC films that is due to quantum confinement effect of the SiC nanocrystallites. The PL results also showed that the intensity of blue luminescence varies and the PL peak shifts to short wavelength side with the change of etching time.