Structural properties of CdS-doped glass nanocrystallites grown by pulsed laser deposition in high vacuum

By conventional pulsed laser deposition followed by in situ annealing in hi gh vacuum, we have successfully fabricated CdS-doped glass (CDG) nanocrysta lline thin films on Si substrates. Photoluminescence (PL) spectra of CDG fi lms show an emission band at about 539 nm (2.30 eV), which is attributed to a new CdO composite formed by the interaction of the CdS nanoparticles and SiO2 in the film. The PL spectrum arising from the CdO band-band transitio n has a peak intensity which depends only on deposition times and not on th e annealing treatment of the film. However, higher annealing temperatures y ielded a greater crystalline size of CdO, as is evident from the resulting redshift of the CdO band in the PL spectra. The presence of CdO in the film s was further confirmed by both energy dispersive x-ray and x-ray diffracti on (XRD) measurements. Its growth in crystalline size with annealing temper ature was also confirmed by analysis of the diffraction peak lines in the X RD spectra. Furthermore, XRD measurements also reveal that the crystal dire ction of the films was greatly determined by the annealing temperature. Fin ally, transmission electron microscopy pictures reveal the three different nanocrystalline structures of CDG corresponding to the different films prod uced with different heat treatments. (C) 2001 American Vacuum Society.