Tham khảo tài liệu 'properties and applications of silicon carbide part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 82 Properties and Applications of Silicon Carbide Fig. 5. Arrhenius plots of the linear rate constant B A for C- and Si-faces. been proposed 7-12 . Among them Massoud et al. 8 9 have proposed an empirical relation for the oxide thickness dependence of oxidation rate that is the addition of an exponential term to the D-G equation dX dt B X A 2X Cexn Ĩ 2 where C and L are the pre-exponential constant and the characteristic length respectively. We have found that it is possible to fit the calculated values to the observed ones using eq. 2 much better than using eq. 1 in any cases as shown by the dashed and solid lines respectively in Figs. 1-4. We discuss the temperature and oxygen partial pressure dependencies of the four parameters B A B C and L below. Arrhenius Plots of the Fitting Parameter Figure 5 shows the Arrhenius plots of the linear rate constant B A for C- and Si-faces. The values of B A for Si-face are one order of magnitude smaller than those for C- face at any studied temperature which is in agreement with the well-known experimental result indicating that the growth rate of Si-face is about 1 10 that of C-face. In the case of Si-face the observed values of B A are on a straight line with an activation energy of eV. While for C-face the values are on two straight lines suggesting the existence of two activation energies . and eV and the break point in the activation energy is around 1000 C 14 . As we have measured the growth rates of SiC Si-face in the oxide thickness range less than 100 nm the diffusion limiting-step regime in which the growth rate is inversely proportional to X does not appear regardless of the temperatures used in this study. Therefore the precision in determining the values of B related to the diffusion coefficient is not sufficient and thus we do not discuss the value of B in this report. Growth rate enhancement of silicon-carbide oxidation in thin oxide regime 83 4- 4 2 100 4 __ 2 a 10 4 2 1 .
