Structure and electrical properties of boron-added (Ba,Sr)TiO3 thin films fabricated by the sol-gel method

• Published in: Thin solid films 1998-09, Vol.330 (2), p.89-95
• Main Authors: Jang, Soo-Ik, Jang, Hyun M.
• Format: Article
• Language: English
• Subjects: Boron; BST thin film; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric properties of solids and liquids; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Niobates, titanates, tantalates, pzt ceramics, etc; Physics; Schottky emission; Sintering additive; Sol-gel
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(98)00560-4

Thin films of BaxSr1−xTiO3 (BST, with x=0.5) were fabricated on a RuO2/Ru/SiO2/Si substrate by the spin coating of the multicomponent sol prepared using metal alkoxides. Boron alkoxide was intentionally introduced to establish a better microstructure and to reduce the leakage current. AFM indicated that a crack-free uniform microstructure having a smooth surface was gradually developed with increasing boron content. The relative dielectric permittivity of the 250-nm thick BST thin films fired at 700°C decreased with increasing content of boron, from 420 for the undoped film to 190 for the 10 mol% boron-added film at 1 MHz. This observation was interpreted in terms of a serial capacitance composed of the perovskite BST grain and the interfacial B2O3 glassy phase having a low dielectric permittivity. The leakage current density (J) also decreased with the amount of boron added. The leakage current for the applied voltage greater than 1 V showed a linear variation of logJ with E1/2 at room temperature, suggesting that the interface-controlled Schottky emission was the dominant conduction process for the BST thin films fabricated on the RuO2 electrode.