Nitrogen transport in float-zone and Czochralski silicon investigated by dislocation locking experiments

Dislocation locking experiments have been used to investigate nitrogen-doped float-zone silicon (NFZ-Si). Experiments on NFZ-Si with a nitrogen concentration of 2.2 × 10 cm were carried out at different annealing temperatures (550–830 °C) for different annealing times (0–1500 hours) and experiments on NFZ-Si with a nitrogen concentration of 3 × 10 cm were carried out at 600 °C for 0–1200 hours. After an initial rise, the unlocking stress was found to saturate for all combinations of conditions investigated. The rate of the initial rise was found to be consistent with diffusion by a dimeric nitrogen species. The saturation value of the unlocking stress was found to be dependent on the nitrogen concentration. Experiments were also carried out on nitrogen-doped Czochralski silicon (NCz-Si) with an oxygen concentration of 5.74 × 10 cm and a nitrogen concentration of 2.10 × 10 cm at 600 °C from 0–5 hours. The dislocation locking due to oxygen appeared to be unaffected by the presence of nitrogen for the conditions investigated.