ZnO has recently become a very popular material due to its great potential for optoelectronics applications. The large direct band gap of 3.3 eV

along with the large exciton binding energy (60 meV) and many other advantages

make ZnO a strong candidate for the next generation of ultraviolet light emitting and lasing devices operating at high temperatures and in harsh environments. The ZnO based light emitting diode (LEDs) will be brighter than the current state-of-art nitride light emitters

and at the same time

the production cost will be reduced significantly compared with current technology. The pulsed laser deposition (PLD) technique has been proved to be a very effective method to deposit high-quality films with complex composition. This technique has some other advantages such as deposition in controllable oxygen partial pressure

high controllability of film composition and growth process

and relatively high deposition rates. In this paper

the ZnO films were deposited on single-crystalline Si(100) substrates by pulsed laser deposition (PLD) method. X-ray diffraction (XRD)

atom force microscope (AFM)

transmission electron microscope (TEM)and photoluminescence (PL) spectrum measurements were employed for the investigation of crystal quality and light emitting performance. The dependence of crystal quality and photoluminescence performance on the growth temperature and oxygen partial pressure was investigated. The results indicate that high-quality ZnOthin films with perfect

c

-axis preferred orientation and smooth and dense microstructure have been successfully grown under optimized conditions (700℃

20 Pa). The near-band-edge emissions in PL spectra are greatly enhanced and the deep level emissions are weakened with the increase of oxygen pressure due to the improvement of stoichiometry

the ZnO films grown under high O

2

pressure (20 Pa) are well close to stoichiometry and of optically high quality. Therefore

it can be concluded that the PL spectra depend on the stoichiometry and the microstructure of the film. The achievement reported here will be used to control the optical properties of ZnOthin films for optical device applications.