Fabrication of isolated ferroelectric nanostructures
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Fabrication of isolated ferroelectric nanostructures S. Bhattacharyya(a), Soma Chattopadhyay(•) and M. Alexe Max Planck Institute of Microstructure Physics Weinberg 2, D-06120 Halle, Germany ABSTRACT In this report, we explore the possibilities of the fabrication and characterization of ferroelectric nano-structures by various methods. Techniques include the self-assembly route and direct electron beam lithography. The chemical self-assembly route, which adopted the microemulsionmediated synthesis, appeared to be very encouraging for producing very small monodispersed nano particles and powders, with sizes of 10-60 nm. The possibility to form a two dimensional arrangement of these micro droplets was explored with a suitable choice of the substrate material, and the method of coating. For the patterns prepared by the e-beam technique, a strong coupling between two closely spaced nano elements was observed, the spacing between them was found to be the key factor in tailoring their interaction, i.e., whether they would arrange themselves in rod-like pattern or a two dimensional array of isolated squares or circles. INTRODUCTION The quest for understanding nano particle processing methods is a natural consequence of the extensive activities carried out in the last decade that resulted in decreasing the size of electronic devices [1,2]. At present there are many ongoing research activities to explore the most rational and reproducible means of fabricating nano-patterns in a controlled manner [3,4]. Ferroelectrics are known to be a special class of functional materials that are promising for nano-scale applications such as in high density memory devices, miniaturized sensors and transducers [5,6]. It is therefore highly relevant to the scientific community to fabricate and study ferroelectric materials at the nanoscale level. In this paper, we are comparing the results of our attempts to fabricate ferroelectric nanostructures using both “top down” and “bottom up” approaches. The systems chosen were simple perovskites such as BaTiO3, and Pb(Zr0.40,Ti0.60)O3, for their relative ease of fabrication. In the chemical “self assembly” route, we have employed the microemulsion mediated synthesis [7,8] of monodispersed nano-particles (dispersed in a liquid medium). Although getting a regular arrangement of these particles on a solid surface is still in its infancy, it is possible to get isolated nano dots with reasonably uniform sizes. There was an agglomeration problem associated with the highly reactive fine particles which could be overcome by the method of peptization [9]. The “top down” method used was electron beam lithography, and the subsequent developing of appropriately prepared films. The substrate material, the electron beam intensity, the interval between the e-beam irradiated regions, and the choice of precursor were the deciding factors in the final size of the nano dots.
(a) (•)
Contact author: [email protected] CSRRI-IIT, MRCAT Sector 10, Advanced Photon Source, Building 433B, Argonne National Lab, A
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