The Synthesis And Characterization Of Photoluminescent Of SiC、Si And CdS Semiconductor Nanocrystals

Because the demand of fluorescent biological labels、near-white emitting QD-LED and solar cells, the research on high quality luminescent semiconductor nanocrystals is very necessary, and this is also the present research focus.This paper focuses on the influences on the growth of SiC quantum dots by a hydrothermal method caused by different reaction conditions such as holding temperature, and holding time. The morphology characterization, the control of morphology and size, the growth mechanism and photoluminescent (PL) properties of the QDs have been studied in detail in the paper.SiC nanocrystals have been prepared from silicon monoxide and OA by the hydrothermal method with the temperature of470℃, pressure of12～15MPa without metallic-catalysts and templates. The TEM, SEM, AFM and HRTEM were employed to check the morphology of the final products, and we found that we synthesized SiC quantum dots with average diameters about5nm±0.5. The research results demonstrate that the QDs have strong photo luminescence at the ultraviolet range.According to the results of the contrast experiments and water behavior at high temperature and pressure, the optimum conditions have been obtained and the growth mechanism has been discussed.CdS quantum dots wer synthesized through the organometallic approach.The size-tunable photo luminescent (PL) CdS nanocrystals were synthesized through this method.During the experiment, precursors were added at a high reaction temperature and epitaxial growth at a low temperature, so the size of CdS quantum dots could be controlled, and then emission color could be controlled too. The precursors were prepared under Ar flow at200℃, until the mixture was completely dissolved and it forms an optically clear solution. The injection occurred at280℃, the S solution was swiftly injected into the flask. After the injection, the temperature was set at250℃for the growth of the nanocrystals. The reaction time was controlled from60s to3600s.The UV-vis and PL spectra of the aliquots were recorded. The TEM、SEM and HRTEM were employed to check the morphology of the final products.From the PL spectra of several CdS nanocrystal, it showed that samples with bigger radius emitted longer wavers, and the fwhw was wider.Si nanowires have been prepared from silicon monoxide by the more cheaper and more greener hydrothermal method.And we found that the Raman spectrum of SiNWs had about2cm"1Red shift and asymmetric broaden. But the PL spectrum of SiNWs showed that it had no more optical value.