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 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 - 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 - 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 and 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 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
