Research On Structural And Photoluminescence Properties Of Silicon Nanocrystals Embedded In SiC Matrix Prepared

Due to novelty nanostructure, Silicon nanocrystals can emit visible light and exhibit novel optoelectronic properties and special structure. Si nanocrystals (Si NCs) embedded in a dielectric matrix are widely considered as a promising material for potential applicationain the fields of Si-based optoelectronic devices and third generation photovoltaic solar cells.On the basis of reviewing the development of Si nanocrystals films, the prepared method, experimental design, structural and photoluminescence properties of silicon nanocrystals embedded in SiC matrix are detailedly researched in this paper. The different types of Si-rich Si1-xCx/SiC nanomultilayer films have been successfully prepared by magnetron co-sputtering and subsequently thermal annealed in an Ar atmosphere. The surface topography, microstructure, and photoluminescence are characterized by X-ray diffraction, Raman spectrometry, FTIR spectrometry, PL spectrometry, AFM and SEM. Based on this research, the origin of PL is discussed.When the sputtering pressure is 0.6 Pa using purity Ar as the sputtering gas, the surface of the as-deposited Si1-xCx/SiC nanomultilayer is compact and smooth, and the distribution of grain is uniform. The crystal structure of Si1-xCx/SiC nanomultilayer films deposited at room temperature and annealed at low temperature is amorphous. As the annealing temperature increases to high temperature, Si NCs and/or SiC NCs gradually begin to form, Si NCs embedded in SiC matrix have formed. By using a different the ratio of area Si and SiC in the sputtering target, Si NCs can be obtained at a differnet annealing temperature. With the increase of the ratio of area Si and SiC, the crystallization temperature of Si Ncs embedded in a SiC matrix lowers. Moreover, the average size of Si NCs gradually increases with the increase of the annealing temperature and the ratio of area Si and SiC. Due to oxygen absorption during annealing or depositing, the interstitial and nonbonded oxygen atoms will be allowed to diffuse to the oxygen vacancy sites, diffusion of oxygen to resultant dangling bond centers can lead to the improvement of passivation degree of Si dangling bonds. With the increase of annealing temperature and the ratio of area Si and SiC, two photoluminescence (PL) peaks have an obvious redshift, respectively, and the intensity of high-energy PL peak gradually enhances, however the change of intensity of low-energy PL peak is unlike. The low-energy PL peak might attribute to dangling bonds defect in amorphous Si sublayers, and the redshift of this peak might be related to the passivation degree of Si dangling bonds. Whereas the origin of the high-energy PL peak may be the emergence of Si NCs, the redshift of this peak correlates with the change in the size of Si NCs.