ZnO films were deposited on Si substrates by MOCVD.Two sets of MO sources were used here.One was Zn(C

2

H

5

)

2

(DEZ) and CO

2

another was Zn(CH

3

)

2

(DMZ) and H

2

O.The carrier gas was nitrogen instead of hydrogen

in order to avoid ZnO decomposed in hydrogen at high temperature.During growth process

the pressure in reactor chamber was 6000Pa and atmosphere

respectively.The growth temperature employed in the experiments were 500

550

600

650 and 700℃.Growth time was 1 hour for all samples.After growth

every sample was cut to two parts.One of them was annealed in air at 900℃ for 1 hour.The structures and photoluminescence properties at room temperature of the as deposited and annealed samples were investigated.It was found that the structure and photoluminescence properties of the ZnO films markedly depends on the MO source

growth pressure and temperature.Only low growth pressure is useful for deposition of ZnO films.As using Zn(C

2

H

5

)

2

and CO

2

the films deposited at 500℃ are all c axis oriented.When the growth temperature increases

the ZnO(002)diffraction peak of the samples became low and low and other ZnO diffraction peaks increase.That means the orientation of crystal grains in the films tends bad

and the film becomes polycrystal.When the growth temperature was at 650℃

not only ZnO but also ZnO

2

peaks appeared in XRD patterns.These properties exhibit more remarkable after samples were annealed.As the growth temperature was at 700℃

ZnO films can't be deposited on Si substrates. The AT PL spectrum of the sample deposited at 500℃ includes two emission peaks

their wavelength are 380nm and 520nm

respectively.After annealing

only one stronger 380nm peak is observed.But the appearance of ZnO

2

in the samples grown at 650℃ changes the photoluminescence spectra.For the as prepared films

the PL spectrum has one peak

the wavelength is 374nm

and a new emission peak with 575nm appears after annealing. Using Zn(C

2

H

5

)

2

and H

2

O

the deposited ZnO films are composed by high-pressure phase of ZnO.The PL spectrum of the sample grown at 550℃ exhibits green emission whose wavelength is 520nm.The emission peak of the sample grown at 450℃ shifts to 345nm.Its energy

about 3.6eV

is larger than the band gap of ZnO.The forming and effects of high pressure phase of ZnO needs to be researched in detail.