There are many viewpoints about green emission center in ZnO films

such as V

O

(donor) or O

Zn

(acceptor). In order to control the emission spectra

it's important to find out green centers of ZnO films. ZnO films were grown on Si substrates by DC reaction sputtering. After growing the samples were heat treated in different temperatures and oxygen partial pressures. X-ray diffraction patterns indicate all films have ?0002〉 preferred orientation

but the film treated in 1000℃ in N

2

ambience has a lattice constant larger than that of other samples and its lattice was larger distortion in lattice. We guess that a lot of interstitial zinc (Zn

i

) was generated in the film

as a result of annealing in the ambience of lack of oxygen. Depth analysis of element contents by Auger electron spectroscopy (AES) indicates the distributions of Zn and O in ZnO films were different due to different annealing conditions. Photoluminescence spectra of all films show two emission peaks at 3.18eV (ultraviolet) and 2.38eV (green)

except the Sample 1

#

(annealed in N

2

)

which has a 3.18eV peak only. Comparing photoluminescence spectra of the films to the distributions of Zn and O by AES in the films

it was found that if O content exceeds that of Zn in any depth of film

the films generate green emission

and the green emission is stronger the more excess of O content. If O content exceeds Zn

the acceptors defects exceed donors in the monophase films. Therefore we suggest that green luminescence center is concerned in acceptor defects in ZnO grown on Si substrates by DC sputtering

the energy of green luminescence

2.38eV

is centered O

Zn

comparing with energy band calculation.