Quality improvement of ZnO layer on LT-grown ZnO layer/Si(111) through a two-step growth using an RF magnetron sputtering

The marked improvement of both the structural and optical quality has been achieved in high-temperature ZnO layers on the low-temperature (LT) ZnO layer/Si(111) through a two-step growth using an RF magnetron sputtering system. From the XRD and SEM observations, it was identified that the full-width at half-maximum (FWHM) of ZnO(0002) omega-rocking curve becomes more narrow and the film surface changes more flat with an introduction of LT-grown layer, indicating that LT ZnO layer can serve as a good template for the growth of high-quality ZnO at high temperatures. In addition to the improvement of crystal quality, photoluminescence (PL) spectra taken from the ZnO film with LT-grown ZnO layer at room temperature and 10 K showed the remarkably improved features including the narrower FWHM of exciton emission, the suppression of the defect-induced visible emission, and the appearance of free exciton peak in comparison with the PL spectra of the directly grown ZnO on Si. (C) 2004 Elsevier B.V. All rights reserved.