Properties of Tio 2 thin films deposited on PET substrate for high energy density capacitor

Research output: Contribution to journalArticlepeer-review

Abstract

TiO 2 thin films for high energy density capacitors were prepared by r.f. magnetron sputtering at room temperature. Flexible PET (Polyethylene terephtalate) substrate was used to maintain the structure of the commercial film capacitors. The effects of deposition pressure on the crystallization and electrical properties of TiO 2 films were investigated. The crystal structure of TiO 2 films deposited on PET substrate at room temperature was unrelated to deposition pressure and showed an amorphous structure unlike that of films on Si substrate. The grain size and surface roughness of films decreased with increasing deposition pressure due to the difference of mean free path. X-ray photoelectron spectroscopy (XPS) analysis revealed the formation of chemically stable TiO 2 films. The dielectric constant of TiO 2 films was significantly changed with deposition pressure. TiO 2 films deposited at low pressure showed high dissipation factor due to the surface microstructure. The dielectric constant and dissipation factor of films deposited at 70 mTorr were found to be 100~120 and 0.83 at 1 kHz, respectively. The temperature dependence of the capacitance of TiO 2 films showed the properties of class I ceramic capacitors. TiO 2 films deposited at 10~30 mTorr showed dielectric breakdown at applied voltage of 7 V. However, the films of 500~300 nm thickness deposited at 50 and 70 mTorr showed a leakage current of ~10 -8~10 -9 A at 100 V.

Original languageEnglish
Pages (from-to)409-415
Number of pages7
JournalKorean Journal of Materials Research
Volume22
Issue number8
DOIs
StatePublished - Aug 2012

Keywords

  • Capacitor
  • Dielectrics
  • High energy density
  • R.f. Sputtering
  • Tio

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