Deep-level transient spectroscopic measurements were made of N-doped (6 x 1015 to 8 x 1017/cm3) layers. Hole traps with activation energies for hole emission of 0.75eV (Co), 0.65eV (C1), 0.79eV (C2) and 0.73eV (D) were detected. The densities of the C1 and C2 traps increased with increasing doping level. The Co and C1 traps were the predominant traps in lightly doped samples, while the C2 trap was the predominant trap in samples with dopant levels of more than 2 x 1017/cm3. Samples which contained a high density of C2 traps exhibited donor-acceptor pair emission bands with decreased peak energies. The C2 trap was thought to be related to the VSe-N complex and to be responsible for carrier compensation.

T.Matsumoto, K.Egashira, T.Kato: Journal of Crystal Growth, 1996, 159, 280-3