The structure and photoluminescence (PL) at room temperature of ZnO films deposited on Si( I 1 I) substrates by metal-organic chemical vapor deposition (MO-CVD) using diethylzinc (DEZ) and CO2 was investigated. It was found that these properties strongly depend on growth temperature and pressure. ZnO films can be deposited only at low pressure and in the temperature region of 500-650 C. The samples grown at certain conditions can generate stronger luminescence of ZnO. When the growth temperature increased to 650 C, the ZnO2 phase was observed in X-ray diffraction (XRD) patterns of the samples. This characteristic became evident after the samples annealed. Appearance of a ZnO, phase results in production of a new emission band centered at 575 nm in the PL spectrum at room temperature, and the green emitting band also disappears.