High quality ZnO thin films grown by plasma enhanced chemical vapor deposition

High quality ZnO thin films have been grown on a Si(100) substrate by plasma enhanced chemical vapor deposition using a zinc organic source [Zn(C2H5)(2)] and carbon dioxide (CO2) gas mixtures at the low temperature of 180 degreesC. The dependence of ZnO thin film quality on the gas flow rate ratio of Zn(C2H5)(2) to CO2 (GFRRZC) is studied by using x-ray diffraction (XRD), optical absorption (OA) spectra, and cathodoluminescence (CL) spectra. High quality ZnO thin films with a c-axis-oriented wurtzite structure are obtained when the GFRRZC is 0.33. XRD shows that the full width at half maximum of (0002) ZnO located at 34.42 degrees is about 0.2 degrees. At room temperature, a pronounced free exciton absorption peak around 365 nm is clearly observed. Also, a strong free exciton emission without deep level defect emission is observed around 385 nm, and its temperature dependence is studied from the photoluminescence spectra. These observations indicate the formation of a high quality ZnO film. Additionally, nitridation of the Si surface caused by releasing NH3 plasma into the deposition chamber is an effective way to improve film quality. (C) 2002 American Institute of Physics.