Fabrication and Characterization of Graphene-Barium Titanate-Graphene layered capacitors by spin coating at low processing temperatures

Abstract

Barium titanate, BaTiO3 (BT), materials have been synthesized by two different routes: one ball-mill-derived (BMD) nanopowder and another precursor-derived (PCD) BT synthesis method were used separately to fabricate BT thin films on stainless steel (SS) and quartz substrates by spin coating. Then thin films from both synthesis routes were characterized by Ultraviolet-Visible-Near Infrared (UV-Vis-NIR) Spectroscopy, Field-Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffractometry (XRD), Raman Spectroscopy, and Four-point collinear probe; all carried out at room temperature. Our studies revealed that the PCD synthesis process did not produce the BT phase even under the 900^0C air-annealing condition. In contrast, a homogeneous BT thin film has been formed from the BMD-BT nanopowder. The optical band gap of BMD-BT thin films was found in the 3.10 - 3.28 eV range. Finally, a Graphene-Barium Titanate-Graphene (G-BT-G) structure was fabricated on a SS substrate by spin coating at processing temperatures below 100^0C and characterized by two different pieces of equipment: a Potentiostat/Galvanostat (PG-STAT) and a Precision Impedance Analyzer (PIA). The G-BT-G structure exhibited a capacitance of 8 nF and 7.15 nF, a highest dielectric constant of 800 and 790, and a low dielectric loss of 4.5 and 5, investigated by PG-STAT and PIA equipment, respectively.