The stresses required to un-pin a dislocation from nitrogen impurities in nitrogen-doped float-zone silicon, and from oxygen impurities in Czochralski silicon, were measured as a function of the unlocking duration. Other experiments measured the dislocation unlocking stress at 550C in nitrogen-doped float-zone silicon, annealed at 500 to 1050C. The results permitted the effective diffusivity of nitrogen in silicon at 500 to 750C to be deduced, yielding:

D (cm2/s) = 2 x 105exp[-3.24(eV)/kT]

This effective diffusivity was consistent with previous measurements made at higher temperatures using secondary ion mass spectrometry.

C.R.Alpass, J.D.Murphy, R.J.Falster, P.R.Wilshaw: Journal of Applied Physics, 2009, 105[1], 013519