Relationship between total arsenic and electrically active arsenic concentrations in silicon produced by the diffusion process

The dependences of diffusion coefficient of As, D_As, upon total As concentration, C_T, and the relationships between C_T and resistivity ρ for several diffusion temperatures are experimentally obtained for the As diffusion into p-type Si from doped polycrystalline-Si sources in the temperature range 850-1050°C. It is found that the relationship between C_T and ρ is dependent upon diffusion temperature for C_T above 10²⁰ cm^-3. The relationship between C_T and electrically active As concentration at diffusion temperature, C_A, i.e., C_T=C_A+(3. 2×10^-6/n³_i) C⁴_A can be obtained, assuming that only electrically active As is mobile and is diffused by the single-level vacancy mechanism, and using the experimental result that the dependence of D_As/D_i (D_i is the intrinsic diffusion coefficient of As) upon C_T/n_i (n _i is the intrinsic electron concentration) is not influenced by diffusion temperature. Using the above equation, it is found that the relationship between C_A and ρ is independent of diffusion temperature, even for C_A above 10²⁰ cm^-3, and can be approximated for C_A above 10²⁰ cm^-3 by an empirical equation: ρ=8.7×10⁴ C^-2/5 _A.