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Epitaxial Growth of Ferroelectric Titanate Layers by Sol-Gel Routes

Epitaxial Growth of Ferroelectric Titanate Layers by Sol-Gel Routes. Muhammad Salameh Prof. Eric P. Kvam. Objectives. Show BaTiO3 is an insulator Adjust orientation and control strains Control growth Integrate with Joel (did not have chance to attempt)

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Epitaxial Growth of Ferroelectric Titanate Layers by Sol-Gel Routes

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  1. Epitaxial Growth of Ferroelectric Titanate Layers by Sol-Gel Routes Muhammad Salameh Prof. Eric P. Kvam

  2. Objectives • Show BaTiO3 is an insulator • Adjust orientation and control strains • Control growth • Integrate with Joel (did not have chance to attempt) • Reduce fatigue of polarization; Increase Lifetime • After certain amts of switching there has been degradation of performance and poor retention of stored information

  3. What is a Ferroelectric? A Ferroelectric Material (Crystal): • Exhibits spontaneous electric polarization below Curie Temperature • Has polarization that can be reversed by application of an electric field • Permanent electric dipole moment possessed by all pyroelectric (polar) materials that may be reoriented by the application of an electrical field

  4. Why Barium Titanate? • Chemical Formula - BaTiO3 • In the pure form it is an electrical insulator • When doped to be a semi-conductor it exhibits positive temperature of co-efficient of resistivity (PTCR) properties in the polycrystalline form • Has high Tc and Pr over singe crystals • Also BaTiO3 exhibits ferroelectric properties and is an excellent photorefractive material

  5. Preparation of Sol-Gel Films • Cutting and Cleaning Substrates • Make Sol-Gel (process of making the thin films) solution • Spin Coating • Low Temp./ High Temp Annealing • Metallography, XRD, Optical Microscopy, SEM • Top electrode and Probe Station

  6. Example of Substrate

  7. Metallography

  8. SEM Pictures

  9. Probe Station

  10. Hysteresis

  11. Capacitance v. Voltage

  12. XRD

  13. XRD Plot

  14. XRD Plot

  15. BaTiO3 on MgO Substrate • Why? • Has crystalline structure that match the thin film • i.e. grow epitaxially • Chemically compatible • Film deposited on substrate, film and substrate will expand equally when annealed • Thermal expansion rates different then substrate will strain or break film

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