Out-diffusion of deep donors in nitrogen-doped silicon and the diffusivity of vacancies

A strong resistivity increase in annealed nitrogen-doped silicon samples was reported long ago-but has remained not fully understood. It is now shown that the complicated evolution of the resistivity depth profiles observed can be reproduced by a simple model based on the out-diffusion of some relevant species. Two versions of such an approach were analyzed: (A) out-diffusion of deep donors treated as VN (off-centre substitutional nitrogen), (B) out-diffusion of vacancies (V) and interstitial trimers (N-3) produced by dissociation of VN3. Version B, although more complicated, is attractive due to a coincidence of the deduced vacancy diffusivity D-V at 1000 degrees C with the value extrapolated from low-temperature data by Watkins. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731796]