Manipulation of the morphology of semiconductor-based nanostructures from core-shell nanoparticles to nanocables: The case of CdSe/SiO2

The morphology of CdSe/SiO2 was manipulated from core-shell-structured nanoparticles to nanocables by using a chemical vapor deposition (CVD) process. The growth of nanocables, with cores no more than 20 mn in diameter, is initiated by the formation of core-shell nanoparticles with SiO2 as matrix and CdSe clusters dispersed inside. After the subsequent vaporization of the SiO2 matrix, the follow-up CdSe vapor crystallizes with the remaining CdSe clusters as nuclei to form CdSe nanowires as the furnace was cooled to 1200 degrees C. During the controlled cooling of the furnace, the SiO vapor re-deposits to sheathe the nanowires. The thickness of the shell and the diameter of core were successfully controlled. The photoluminescence measurements show that the CdSe/SiO2 nanocables have strong visible-light emission bands located at 590 and 688 nm, which are attributed to the defects induced by SiO2 sheaths nanowires and the quantum confinement effect of the CdSe, respectively. The UV/Vis absorption spectra of the naked CdSe nanowires further validate the above-mentioned quantum confinement effect. The deterministic growth of these nanocables is very important for the design of the nanodevices based on them.