中国物理B ›› 2017, Vol. 26 ›› Issue (1): 10702-010702.doi: 10.1088/1674-1056/26/1/010702

• GENERAL • 上一篇    下一篇

Morphological and electrical properties of SrTiO3/TiO2/SrTiO3 sandwich structures prepared by plasma sputtering

Saqib Jabbar, Riaz Ahmad, Paul K Chu   

  1. 1. Government College University, Lahore 54000, Pakistan;
    2. Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong, China
  • 收稿日期:2016-09-05 修回日期:2016-10-26 出版日期:2017-01-05 发布日期:2017-01-05
  • 通讯作者: Saqib Jabbar E-mail:saqib.jabbar@gcu.edu.pk
  • 基金资助:

    Project supported by the City University of Hong Kong Applied Research Grant (ARG) of China (Grant No. 9667122). One of the authors, Mr. Saqib Jabbar, is grateful to the Higher Education Commission (HEC) of Pakistan for financial support under IRSIP.

Morphological and electrical properties of SrTiO3/TiO2/SrTiO3 sandwich structures prepared by plasma sputtering

Saqib Jabbar1,2, Riaz Ahmad1, Paul K Chu2   

  1. 1. Government College University, Lahore 54000, Pakistan;
    2. Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong, China
  • Received:2016-09-05 Revised:2016-10-26 Online:2017-01-05 Published:2017-01-05
  • Contact: Saqib Jabbar E-mail:saqib.jabbar@gcu.edu.pk
  • Supported by:

    Project supported by the City University of Hong Kong Applied Research Grant (ARG) of China (Grant No. 9667122). One of the authors, Mr. Saqib Jabbar, is grateful to the Higher Education Commission (HEC) of Pakistan for financial support under IRSIP.

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摘要：

SrTiO3 (STO) and TiO2 are insulating materials with large dielectric constants and opposite signs of the quadratic coefficient of voltage (α). Insertion of a TiO2 thin film between STO layers increases the linearity of the capacitance in response to an applied voltage, to meet the increasing demand of large-capacitance-density dynamic random access memory capacitors. Both STO and TiO2 suffer from the problem of high leakage current owing to their almost equivalent and low bandgap energies. To overcome this, the thickness of the thin TiO2 film sandwiched between the STO films was varied. A magnetron sputtering system equipped with radio frequency and direct current power supply was employed for depositing the thin films. TiN was deposited as the top and bottom metal electrodes to form a metal-insulator metal (MIM) structure, which exhibited a very large linear capacitance density of 21 fF/um2 that decreased by increasing the thickness of the TiO2 film. The leakage current decreased with an increase in the thickness of TiO2, and for a 27-nm-thick film, the measured leakage current was 2.0×10-10 A. X-ray diffraction and Raman spectroscopy revealed that TiN, STO, and TiO2 films are crystalline and TiO2 has a dominant anatese phase structure.

关键词: strontium titanate, Raman spectroscopy, plasma deposition, MIM capacitor

Abstract:

SrTiO3 (STO) and TiO2 are insulating materials with large dielectric constants and opposite signs of the quadratic coefficient of voltage (α). Insertion of a TiO2 thin film between STO layers increases the linearity of the capacitance in response to an applied voltage, to meet the increasing demand of large-capacitance-density dynamic random access memory capacitors. Both STO and TiO2 suffer from the problem of high leakage current owing to their almost equivalent and low bandgap energies. To overcome this, the thickness of the thin TiO2 film sandwiched between the STO films was varied. A magnetron sputtering system equipped with radio frequency and direct current power supply was employed for depositing the thin films. TiN was deposited as the top and bottom metal electrodes to form a metal-insulator metal (MIM) structure, which exhibited a very large linear capacitance density of 21 fF/um2 that decreased by increasing the thickness of the TiO2 film. The leakage current decreased with an increase in the thickness of TiO2, and for a 27-nm-thick film, the measured leakage current was 2.0×10-10 A. X-ray diffraction and Raman spectroscopy revealed that TiN, STO, and TiO2 films are crystalline and TiO2 has a dominant anatese phase structure.

Key words: strontium titanate, Raman spectroscopy, plasma deposition, MIM capacitor

中图分类号:  (Vacuum chambers, auxiliary apparatus, and materials)

  • 07.30.Kf
52.77.Dq (Plasma-based ion implantation and deposition) 74.25.nd (Raman and optical spectroscopy) 73.61.Ng (Insulators)