ZnO has awide band gap of 3.37 eV

low lasing power threshold for optical pumping at room temperature

and UV emission resulted from a large exciton binding energy of 60meV

so itcan be used as light emitting diodes (LED)

photodetectors

and shortwave laser. To fabricate the devices

high quality ZnO thin films are often required

such as they should have good crystal properties with high

c

-axis orientation and low stress. Many researches have been done on the preparation of high quality ZnO films in recentyears.