| Abstract
| - A novel spray-based technique was developed for the production of high quality semiconductor nanocrystals, offering an attractive alternative to conventional production methods, epitaxial growth, and colloidal synthesis. The novel spray technique is simple and low cost and overcomes limitations of the previously introduced methods. According to this new spray-based technique, solutions of semiconductor salts are first sprayed via thermospray nebulizer into monodispersed droplets, which subsequently become solid nanocrystals by solvent evaporation. Each semiconductor nanocrystal is produced from a single spray droplet upon the full vaporization of the liquid. The average diameter and size distribution of the final nanocrystals can be controlled and determined by the concentration of the sprayed solution and the droplet size, hence by spray production parameters. Thus, thermospray experimental parameters such as the control temperature, liquid flow rate, and capillary inner diameter were fully examined and optimized for the production of high-quality semiconductor nanocrystals of the desired size and composition. A model is suggested for estimating the mean droplet diameter of the generated thermospray aerosol droplets, and it indicates a trend similar to the observed experimental results. The solubility levels of various semiconductor salts in different solvents were determined by atomic absorption spectroscopy. The results indicate that the solubility is related to the solvent polarity, salt bonding characteristic (ionic or covalent), and the solution pH (presence of NH3).The method is demonstrated through the production of high quality monodispersed (∼5% size distribution) CdS nanocrystals in the size range of 3−6 nm. The further production of PbS nanocrystals, and preliminary results for ZnS and MoS2 nanocrystals, establish the generalization of the method for different types of semiconductors.
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