The formation of donors that were associated with O in N-doped and undoped Czochralski-type material was investigated by means of electrical and infra-red measurements at low temperatures (8K). It was found that donors were not generated in N-doped material which had been annealed (650C, up to 100h). A study was also made of the effect of pre-annealing (450 or 1050C) upon the formation of donors in N-doped material. It was noted that pre-annealing at 450C enhanced the formation of donors during subsequent annealing at 650C, while pre-annealing at 1050C had no effect. The donor concentration increased at 650C, as a function of the pre-annealing time at 450C. The formation of N-O complexes in N-doped material was believed to suppress the generation of donor nuclei, and thereby donor formation.

D.Yang, R.Fan, L.Li, D.Que, K.Sumino: Journal of Applied Physics, 1996, 80[3], 1493-8