Combinatorial Laser Processing Of Dielectric/Ferroelectric Thin and Thick Films
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Combinatorial Laser Processing Of Dielectric/Ferroelectric Thin and Thick Films R. N. Das1, C. Lew1, I. Zergioti2, M. O. Thompson1, E. P. Giannelis1 1. 2.
Cornell University, Department of Materials Science and Engineering, Ithaca, NY Foundation for Research and Technology - Hellas, Institute of Electronic Structure and Laser, Crete, Greece
ABSTRACT A library of different crystalline sol-gel thin films with a composition of BaxTiyOz (where x = 1,2; y = 1,2,9 and z = 3, 7, 20) has been generated using variable multi-step laser and thermal annealing. Point by point X-ray diffraction characterization revealed the presence of high dielectric (BaTiO3) and low dielectric (Ba2Ti2O7 and Ba2Ti9O20) phases. Appropriate laser and thermal annealing controlled crystallinity, phase content, morphology and dielectric property of libraries. We have extended the process to BaTiO3 based thick-films and investigated the surface morphology of laser-annealed films. INTRODUCTION Combinatorial synthesis is an approach that enables the creation of large compositional range “integrated materials chips". Technologies, such as thin film deposition, lithography and high resolution imaging, have enabled and sustained the revolutionary progress in the information industry based on integrated circuit chips. These same technologies are now being applied to revolutionize research in materials. Since the application of combinatorial synthesis to inorganic thin-film materials by a group at the Lawrence Berkeley National Laboratory [1,2], several investigators have focused on improving their processing, properties (electrical impedance, optical, and magnetic) and screening techniques. The intent in all these investigation is to obtain a composition gradient in order to optimize a set of desired localized properties. BaTiO3 based combinatorial thin films are widely pursued for embedded dynamic random access memory (DRAM) capacitors as well as for various tunable microwave device applications [3]. In general, BaTiO3 based libraries with different compositions or stoichiometries are fabricated by combining sequential thin film depositions with physical masking techniques [4]. Codeposition [5] from three spatially separated sources is also used to obtain samples with a natural composition gradient. In both cases the libraries undergo controlled thermal treatments to diffuse and mix the precursors at each site. In the present study, we report the fabrication of a high-density combinatorial thin film library of BaxTiyOz based materials with the objective of tunable capacitance for integral capacitor applications. A library of different crystalline sol-gel thin films with a composition of BaxTiyOz (where x = 1,2; y = 1,2,9 and z = 3, 7, 20) was generated on a 4'' x 4'' Si or glass substrates using variable multi-step laser and thermal annealing. As far as we know, this is the first time multi-step laser annealing has been used to fabricate a
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materials library. We have extended the process to BaTiO3 based thick-films and investigated t
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