Structural and ferroelectric properties of epitaxial La0.5Sr0.5CoO3/Ba0.4Sr0.6TiO3 /La0.5Sr0.5CoO3 thin-film capacitors on silicon for DRAM applications

Pang Jen Kung, David B. Fenner, Qi Li

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Abstract

Epitaxial La0.5Sr0.5CoO3/Ba0.4Sr0.6TiO3 /La0.5Sr0.5CoO3 heterostructures were grown (650-750 °C) on yttria-stabilized zirconia (YSZ)-buffered silicon (100) by pulsed laser (Nd:YAG) deposition. A 15-nm-thick YBa2Cu3O7 film was deposited on the YSZ to act as a template layer for epitaxial growth of the subsequent conductive oxide and ferroelectric film layers. The Ba0.4Sr0.6TiO3 film was (h00) oriented normal to the Si-wafer surface. The temperature-dependent resistance curve measured on the La0.5Sr0.5CoO3 top electrode layer was found to indicate to some extent the film quality of the underlying layers. Hundreds of capacitors, fabricated by wet chemical etching from the as-deposited films, exhibited dc leakage current densities in the range of 0.05-0.1 μA/cm2 at 1-volt operation. By increasing the thickness of the dielectric layer, some of them were able to be tested at up to 20 volts before resistive leakage became dominant. To reduce leakage current densities and increase dielectric constants in these film capacitors for dynamic random access memory (DRAM) applications, we have made efforts to incorporate hybrid Pt/La0.5Sr0.5CoO3 bottom electrodes into capacitors. This results in improved dielectric constants (451 at 10 kHz) and P-E hysteresis characteristics (Ec = 58 kV/cm, Pr = 7.5 μC/cm2, and Ps = 25 μC/cm2).

Original languageEnglish (US)
Pages (from-to)183-188
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume401
Publication statusPublished - Jan 1 1996
EventProceedings of the 1995 MRS Fall Symposium - Boston, MA, USA
Duration: Nov 27 1995Dec 1 1995

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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