p-type ZnO has attracted more and more attention because it is necessary to fabricate ZnO devices based on current injection. More and more improvements on p-type ZnO and p-n junctions are reported. However

electroluminescence in these works was rarely observed. We have already succeed in fabricating a ZnO p-n junction LED on sapphire substrate by using activated NO plasma. Here

N

2

was used as the acceptor dopant and O

2

was used as assistant gas as well as oxygen source. Emission spectra of the N

2

-O

2

plasma were monitored in situ to adjust parameters timely. Electronics measurements of the as-grown p-type ZnO on sapphire shows a carrier concentration of 1.2×10

18

cm

-3

and mobility approach to 1 cm

2

·V

-1

·s

-1

. The LED based on p-n junction shows a certain rectification effect and the turn on voltage is 3.10 V

which is consistent with the bandgap of ZnO. Electroluminescence spectra shows two bands: one is at 420 nm

from donoracceptor pairs; and the other ranges from 500 to 700 nm

which is attributed to the emissions from point defects in ZnO.