The effect of N-O complexes upon the electrical properties of N-rich Czochralski material that had been grown in a N atmosphere was investigated during annealing at temperatures ranging from 650 to 1000C. Electrical and low-temperature (8K) Fourier transmission infra-red spectroscopy revealed that the carrier concentration of the N-rich material varied as a function of the annealing time and temperature. This was attributed to the formation and elimination of N-O complexes which acted as shallow thermal donors. When the N-O complexes were eliminated by annealing at temperatures above 900C, the carrier concentration of the N-rich sample was stabilized. It was suggested that the N-O complexes attracted more O atoms to form new electrically inactive N-O clusters, and thereby lost their electrical activity.

D.Yang, R.Fan, L.Li, D.Que, K.Sumino: Applied Physics Letters, 1996, 68[4], 487-9