Nitrogen-doped ZnSe layers have been grown using dimethylzinc and H₂Se as precursors and N₂ or N₂+3H₂ plasma as a dopant. With decreasing the VI/II flow ratio, N acceptors are incorporated more effectively. In the case of N₂ plasma doping, the intensity of N acceptor-bound exciton emission is much higher than that of donor-bound exciton emission, but the layers exhibit n-type conductivity and the free-electron concentration increases with decreasing the VI/ II ratio. In the case of N₂+3H₂ plasma doping, on the other hand, the layers exhibit high resistivity and, after subsequent rapid thermal annealing at 700°C, some layers show p-type conductivity with hole concentration of∼1×10¹⁵ cm^-3. This indicates that hydrogen causes not only passivation of the N acceptors but also suppression of the generation of donors. Methyl radicals play an important role in producing donor species. Prior to plasma doping, it is needed to prepare Zn-rich surface without methyl radicals in order to obtain p-type N-doped ZnSe layers.