engleski

Direct Ion Beam Synthesis of II-VI Nanocrystals

We have studied the direct synthesis of nanoparticles formed by dual implantation of large and equal doses of Cd+S, Zn+Te, Cd+Te or Pb+Te ions into SiO2 substrate. Grazing incidence small angle X-ray scattering (GISAXS), Transmittance measurements and Raman spectroscopy were used to investigate implanted composites. The 2D GISAXS patterns suggest the synthesis of nanoparticles already during ion implantation, performed either at 300 K or at 77 K, while annealing at higher T causes an increase of the fraction and the average size of synthesized nanoparticles. After high-T annealing both optical methods detected nanocrystals of compound semiconductors CdS, ZnTe, or CdTe through the appearance of the respective first optical gaps, Eg, in transmittance measurements and characteristic LO peaks in Raman spectra. It is proposed that at high ion doses a fraction of implanted atoms synthesize already during implantation into amorphous aggregates of compound semiconductor, which transform into crystalline nanoparticles after annealing.

nanocrystals; implantation; GISAXS; raman; transmittance; CdS; CdTe; ZnTe; PbTe; quantum dots

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