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Tham khảo tài liệu 'silicon carbide materials processing and applications in electronic devices part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 95 The Formation of Silicon Carbide in the SiCx Layers x 0.03-1.4 Formed by Multiple Implantation of C Ions in Si C C Si C Si C Si Si C Si C Si Si Si g b 311 18 17 31 10 16 13 d Fig. 24. Possible variants of both the infrared inactive clusters a-h chains of them b and a flat net of clusters a with various types of bonds between the atoms of Si great circles and C small circles . Bond lengths are presented in pm. It was found that for the layers SiCx with low carbon concentrations Fig. 23 the minimum of IR transmission peak for the TO-phonons is shifted to above 800 cm-1 as the annealing temperature is increased. In the case of SiC0 4 the position of the peak minimum shifts from 725 to 810 cm-1 in the temperature range 20-1100 C and returns to the 800 cm-1 at 1300 C. In the case of SiC0.12 - from 720 to 820 cm-1 in the range 20-1000 C and returns to 800 cm-1 at 1200 C. In the case of SiC0.03 - from 720 to 830 cm-1 in the range 20-1000 C and does not change its position during 1100-1200 C. Displacement of the peak minimum into the region above 800 cm-1 may be due to the presence of SiC nanocrystals of small size 3 nm and an increase in the contribution to the IR absorption amplitude of their surfaces and surfaces of the crystallites Si containing strong shortened Si-C-bonds. For a layer SiC0.12 and SiC0.4 return of the minimum to 800 cm-1 at temperatures of 1100-1400 C may be caused by incorporation of carbon atoms into the nanocrystals of SiC and the growth of their size up to 3.5-5 nm and higher. The observed shift of the peak minimum indicates the following fact the absorbing at low frequencies energetically unfavorable long single Si-C-bonds decay during annealing at 600-1000 C and the stronger short or tetrahedral Si-C-bonds absorbing at higher frequencies are formed. Since the amplitude of IR transmission at 800 cm-1 is proportional to the concentration of tetrahedral oriented Si-C-bonds and the amplitude at a certain frequency is assumed to be proportional to
