Dislocation unlocking experiments were performed using nitrogen-doped float-zone silicon. The dislocation unlocking stress was measured in specimens subjected to annealing for various durations and temperatures. Analysis of the rate of the initial rise in unlocking stress, with annealing time, yielded an activation energy, for nitrogen diffusion, of 3.24eV at 500 to 750C. Numerical simulation of nitrogen diffusion to the dislocation core permitted an approximate value of 2 x 105cm2/s to be estimated for the diffusivity pre-factor. These parameters were consistent with the results of previous higher-temperature secondary ion mass spectrometry out-diffusion experiments. Other measurements, made at up to 1050C and followed by rapid quenching, indicated that the ability of nitrogen to lock dislocations was substantially reduced at high temperatures.

Nitrogen in Silicon, Diffusion at 500–750C and Interaction with Dislocations. C.R.Alpass, J.D.Murphy, R.J.Falster, P.R.Wilshaw: Materials Science and Engineering B, 2009, 159-160, 95-8