Nanopatterning of colloidal nanocrystals emitters dispersed in a PMMA matrix by e-beam lithography

We report on the fabrication of periodic nanostructures embedding semiconductor colloidal nanocrystals (NCs) by directly exposing a polymer/NCs blend to electron beam lithography (EBL). Our technological approach for the fabrication of NCs-based photonic devices relies on the dispersion of CdSe/ZnS core/shell NCs into a layer of polymethilmethacrylate (PMMA) positive electron resist, which is patterned by means of an EBL process. The presence of NCs in the resist did not modify the peculiar behaviour of PMMA, which was selectively removed from the regions exposed to the electron beam. The morphology of the sample was assessed by scanning electron microscopy and atomic force microscopy measurements. The optical analysis of the samples after the dispersion of the NCs into the PMMA matrix and the exposure to the e-beam showed the successful localization of the colloidal NCs, whose emission properties were preserved.