Electrical Properties of Ba0.5Sr0.5Ta2O6 Thin Film Fabricated by Sol-Gel Method

Li LU  Masahiro ECHIZEN  Takashi NISHIDA  Kiyoshi UCHIYAMA  Yukiharu URAOKA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E93-C   No.10   pp.1511-1515
Publication Date: 2010/10/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E93.C.1511
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Frontier of Thin-Film Transistor Technology)
Category: 
Keyword: 
Ba0.5Sr0.5Ta2O6,  gate oxide,  dielectric constant,  leakage current,  

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Summary: 
Ba0.5Sr0.5Ta2O6 (BSTA) thin film was successfully fabricated on a Pt/SiO2/TiO2/Si substrate using the Sol-Gel method. Fundamental electrical properties of the BSTA thin film were investigated using metal-insulator-metal (MIM) structure. No diffusion of ions, from the thin film or the substrate, is observed because of the using of MIM structure. The Root Mean Square roughness of 1.04 nm shows that thin film grew well on the substrate. The BSTA thin film shows a much higher dielectric constant of about 130 than conventional gate insulators and high-k materials that are currently used in Thin Film Transistors. Low leakage current density of about 10-8 A/cm2 was obtained at an applied electric field of 500 kV/cm. Schottky emission is the dominant conduction mechanism at applied electric fields lower than 500 kV/cm and Fowler-Nordheim tunneling is the dominant conduction mechanism at higher applied electric fields. The Schottky barrier height between the Pt electrode and the Ba0.5Sr0.5Ta2O6 thin film was estimated to be 0.75 eV.