The out-diffusion of N from float-zone material was measured by using secondary ion mass spectrometry. The diffusion coefficient was determined at 800 to 1200C. The total amount of N out-diffusion agreed with the change in infra-red absorption during heat treatment. The diffusivity data could be described by:

D (cm2/s) = 2.7 x 103 exp[-2.8(eV)/kT]

These values were 5 orders of magnitude higher than previously reported ones. It was suggested that the former results applied to N-N pair-like molecules, while the latter applied to substitutional N atoms.

T.Itoh, T.Abe: Applied Physics Letters, 1988, 53[1], 39-41