Nanocrystals have been employed in many fields for various applications. We are interested in using nanocrystals for pattern transfer in nanoscale fabrication. The nanocrystals can act as a mask on a substrate, around which the substrate can be etched to realize features in the shape and size of the nanocrystals. These nanocrystals must be monodisperse and of the size of the desired features, which is 5 – 10 nm in this study. Synthetic routes for CaF2 and LaF3 nanocrystals, including solvothermal and autoclave techniques, were examined to determine the best route for making crystals for pattern transfer. For CaF2, the best route for monodisperse spheres used the solvothermal method. However, the particles were too small so were used as seeds in a second synthetic attempt. The particles grew, but the x-ray diffraction pattern did not match the same fluorite phase for CaF2, indicating that a phase or particle change occurred during growth. For LaF3, the best route used the autoclave. The particles synthesized were in the correct size range. However, there were differences in shapes between cubic and hexagonal and a deviation in sizes. This method also converted a fair amount of the precursors into NaLaF4 rods instead of LaF3 crystals, producing a lower yield of the desired nanocrystal. Less stirring before reacting decreased the number of rods but made more polydisperse particles. Filtering helps to rid the sample of the rods, however, there is still a lower yield of LaF3 than is desired. In the future, these synthetic routes will continue to be developed to better synthesize monodisperse nanocrystals in the desired 5 – 10 nm range. These particles will then be tested for their ability to self-assemble and to act as a mask for etching silicon.

Synthesis of CaF2 and LaF3 nanocrystals for use in silicon patterning

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.