ZnO is a multi-function direct wide-band semiconductor material with wurtzite structure.It has potential applications in varistors

phosphors

transparent electrode

optoelectronic devices

blue-purple light devices.n-type low resistivity ZnO is easy to obtain.However

the difficulty of high resistivity ZnO and p type ZnO must be resolved for the purpose of fabricating practical ZnO devices.Although many research groups are working on it

p-type ZnO problem has never been figured out.N is an effective p-type dopant for Ⅱ-Ⅵ group compounds.There are two effects when N is doped in ZnO thin films:providing a shadow acceptor energy level and decreasing concentration of Zn

i

atoms by combining with ZnO.Thus

it is possible to obtain high resistivity and p-type ZnO by doping N atoms in ZnO.There has two kinds of N source

N

2

and NH

3

.In this paper

the behaviors of N

2

and NH

3

doped in ZnO thin films are investigated.Firstly

N

2

was doped in ZnO thin films grown on c-plane sapphire substrate using plasma assisted MOCVD system.Plasma generator of plasma assisted MOCVD system is very efficient to dope N atoms into ZnO films and to obtain high resistivity ZnO thin films.The N

2

doped ZnO films have all of properties of ZnO and show high crystal quality

especially in optical properties

which show light-yellow body color.XRD measurement shows a high intensity peak at 2θ=34.6°with a FWHM of 0.148°

which is(002)peak of ZnO.The corresponding value of double-crystal XRD rocking-curve is 0.34°.The emitting peak locates at 3.29 eV in PL spectrum with a FWHM of 100meV.Compared with 0.65Ω·cm of undoped sample

the resistivity increases to 5×10

4

Ω·cm with N

2

doping.Secondly

the behavior of NH

3

doped ZnO grown on R-plane sapphire has been investigated.After optimized growth conditions

the XED result shows a high intensity peak at 2θ=56.30°with a FWHM of 0.50°

which is

<

110

>

peak of ZnO.The AFM photo shows that the surface of the film is very smooth.The roughness is about 3.01nm.Under different NH

3

flux

the sasple's

resistivity has different value as well as electrica1 conduction type.The p-type sample was obtained when NH

3

flux is 80 sccm with the resistivity of 102Ω·cm

observed by Hall measurement.Finally

we found that the p-type sample has the trend of turning to n-type.This maybe is due to instability of N-Zn bond in N doped ZnO which is investigated by XPS measurements.Consequently

behavior studies of N doping in ZnO are important to achieve high resistivity p-type ZnO thin films.Furthermore

it is maybe possible to obtain better results by annealing samples under protection of N

2

or NH

3

.