Polycrystalline chemical vapor deposited films were studied by using electron spin resonance, light-induced electron spin resonance, and constant photoconductivity methods. This revealed that dispersed substitutional N atoms (P1 centers) were the main paramagnetic form of N in chemical vapor deposited material. It was found that the density of N-related paramagnetic states was strongly affected by illumination and heat treatment. The P1 center in chemical vapor deposited material gave rise to a deep donor state which was about 1.5eV below the conduction band.

C.F.O.Graeff, E.Rohrer, C.E.Nebel, M.Stutzmann, H.Güttler, R.Zachai: Applied Physics Letters, 1996, 69[21], 3215-7