Initial study on the structure and optical properties of ZnO film on Si(1 1 1) substrate with a SiC buffer layer

Using the RF-magnetron sputtering technique, we have fabricated ZnO film on Si(1 1 1) substrate with a SiC buffer layer chosen to reduce the lattice mismatch between ZnO and Si. The as-deposited films were annealed in the temperature range of 600-1000 °C under nitrogen ambient. Then the thin films have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL). According to the measurement results, it was found that the ZnO/SiC/Si(1 1 1) films have better crystal quality than that of the ZnO/Si(1 1 1) films, which is more apparent with the increase of annealing temperature, and after annealed at 1000 °C, two new peak at 870 and 891 cm^-1 in the FTIR spectra appear and are related to the Zn-C and Zn-Si bonds, respectively, indicating the interface between the ZnO and SiC becomes more impacted and complicated. We have also discussed the PL properties of ZnO/SiC in great detail. There are two PL peaks at 376 and 413 nm. The 376 nm band is related to the free-exciton recombination of ZnO and has a great relation to the crystal quality of the ZnO film. The origin of the 413 nm peak is associated with the interface traps existing in the depletion regions between the ZnO-ZnO grain boundaries, which bears on the condition of the interface between ZnO and SiC.