Microstructure and superlattice effects on the optical properties of ferroelectric thin films: Dissertation

Research output: ThesisDissertationCollection of Articles

Abstract

This thesis deals with the microstructure effects on the optical properties of (i) polycrystalline Nd-modified lead-zirkonium-titanate (PNZT) and (ii) highly oriented BaTiO3 (BTO) thin films together with the stacking structure influence on the optical properties of (iii) BaTiO3-SrTiO3 (STO) superlattice thin films. All the films were grown on MgO(001) substrates by pulsed laser deposition. Different structures were obtained by tuning the thin film processing conditions. PNZT thin films were deposited at room temperature and different crystallite size distributions were produced by varying the post-annealing temperature. The refractive index and electro-optic responses were found to increase with increasing mean crystallite size. Oxygen pressure during the film deposition at 700 °C was found to be a very critical parameter to modify the crystallographic and consequent other physical properties of BTO thin films as suggested by the dielectric and optical measurements. Low oxygen pressure films were epitaxial, with elongated lattice parameters along the surface normal, while increased working oxygen pressure produced non-epitaxial films with lattice elongation along the in-plane orientation. An effective electro-optic coefficient of ~21 pm/V was measured for the BTO films. Periodic BTO-STO superlattices were deposited with varying stacking periodicity between 27 and 1670 Å. Birefringence decreased with increasing stacking periodicity, due to relaxation of the lattice strain induced by the layer interfaces. The electro-optic response was found to reach a maximum at a specific stacking periodicity and it decreases with both increasing and decreasing individual layer thickness. The operation of a Mach-Zehnder waveguide intensity modulator based on the BTO-STO superlattice with effective electro-optic coefficient of 73 pm/V was also demonstrated.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Oulu
Award date27 Jun 2008
Place of PublicationEspoo
Publisher
Print ISBNs978-951-38-7102-4
Electronic ISBNs978-951-38-7103-1
Publication statusPublished - 2008
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

electro-optics
optical properties
microstructure
thin films
periodic variations
oxygen
theses
coefficients
optical measurement
elongation
pulsed laser deposition
birefringence
superlattices
modulators
lattice parameters
physical properties
tuning
refractivity
waveguides
annealing

Keywords

  • ferroelectrics
  • thin film
  • electro-optics
  • superlattice
  • PZT
  • BaTiO3
  • SrTiO3

Cite this

@phdthesis{88746bddf0bd460f81c8344f6da46ace,
title = "Microstructure and superlattice effects on the optical properties of ferroelectric thin films: Dissertation",
abstract = "This thesis deals with the microstructure effects on the optical properties of (i) polycrystalline Nd-modified lead-zirkonium-titanate (PNZT) and (ii) highly oriented BaTiO3 (BTO) thin films together with the stacking structure influence on the optical properties of (iii) BaTiO3-SrTiO3 (STO) superlattice thin films. All the films were grown on MgO(001) substrates by pulsed laser deposition. Different structures were obtained by tuning the thin film processing conditions. PNZT thin films were deposited at room temperature and different crystallite size distributions were produced by varying the post-annealing temperature. The refractive index and electro-optic responses were found to increase with increasing mean crystallite size. Oxygen pressure during the film deposition at 700 °C was found to be a very critical parameter to modify the crystallographic and consequent other physical properties of BTO thin films as suggested by the dielectric and optical measurements. Low oxygen pressure films were epitaxial, with elongated lattice parameters along the surface normal, while increased working oxygen pressure produced non-epitaxial films with lattice elongation along the in-plane orientation. An effective electro-optic coefficient of ~21 pm/V was measured for the BTO films. Periodic BTO-STO superlattices were deposited with varying stacking periodicity between 27 and 1670 {\AA}. Birefringence decreased with increasing stacking periodicity, due to relaxation of the lattice strain induced by the layer interfaces. The electro-optic response was found to reach a maximum at a specific stacking periodicity and it decreases with both increasing and decreasing individual layer thickness. The operation of a Mach-Zehnder waveguide intensity modulator based on the BTO-STO superlattice with effective electro-optic coefficient of 73 pm/V was also demonstrated.",
keywords = "ferroelectrics, thin film, electro-optics, superlattice, PZT, BaTiO3, SrTiO3",
author = "Jussi Hiltunen",
note = "Project code: 25779",
year = "2008",
language = "English",
isbn = "978-951-38-7102-4",
series = "VTT Publications",
publisher = "VTT Technical Research Centre of Finland",
number = "684",
address = "Finland",
school = "University of Oulu",

}

Microstructure and superlattice effects on the optical properties of ferroelectric thin films : Dissertation. / Hiltunen, Jussi.

Espoo : VTT Technical Research Centre of Finland, 2008. 86 p.

Research output: ThesisDissertationCollection of Articles

TY - THES

T1 - Microstructure and superlattice effects on the optical properties of ferroelectric thin films

T2 - Dissertation

AU - Hiltunen, Jussi

N1 - Project code: 25779

PY - 2008

Y1 - 2008

N2 - This thesis deals with the microstructure effects on the optical properties of (i) polycrystalline Nd-modified lead-zirkonium-titanate (PNZT) and (ii) highly oriented BaTiO3 (BTO) thin films together with the stacking structure influence on the optical properties of (iii) BaTiO3-SrTiO3 (STO) superlattice thin films. All the films were grown on MgO(001) substrates by pulsed laser deposition. Different structures were obtained by tuning the thin film processing conditions. PNZT thin films were deposited at room temperature and different crystallite size distributions were produced by varying the post-annealing temperature. The refractive index and electro-optic responses were found to increase with increasing mean crystallite size. Oxygen pressure during the film deposition at 700 °C was found to be a very critical parameter to modify the crystallographic and consequent other physical properties of BTO thin films as suggested by the dielectric and optical measurements. Low oxygen pressure films were epitaxial, with elongated lattice parameters along the surface normal, while increased working oxygen pressure produced non-epitaxial films with lattice elongation along the in-plane orientation. An effective electro-optic coefficient of ~21 pm/V was measured for the BTO films. Periodic BTO-STO superlattices were deposited with varying stacking periodicity between 27 and 1670 Å. Birefringence decreased with increasing stacking periodicity, due to relaxation of the lattice strain induced by the layer interfaces. The electro-optic response was found to reach a maximum at a specific stacking periodicity and it decreases with both increasing and decreasing individual layer thickness. The operation of a Mach-Zehnder waveguide intensity modulator based on the BTO-STO superlattice with effective electro-optic coefficient of 73 pm/V was also demonstrated.

AB - This thesis deals with the microstructure effects on the optical properties of (i) polycrystalline Nd-modified lead-zirkonium-titanate (PNZT) and (ii) highly oriented BaTiO3 (BTO) thin films together with the stacking structure influence on the optical properties of (iii) BaTiO3-SrTiO3 (STO) superlattice thin films. All the films were grown on MgO(001) substrates by pulsed laser deposition. Different structures were obtained by tuning the thin film processing conditions. PNZT thin films were deposited at room temperature and different crystallite size distributions were produced by varying the post-annealing temperature. The refractive index and electro-optic responses were found to increase with increasing mean crystallite size. Oxygen pressure during the film deposition at 700 °C was found to be a very critical parameter to modify the crystallographic and consequent other physical properties of BTO thin films as suggested by the dielectric and optical measurements. Low oxygen pressure films were epitaxial, with elongated lattice parameters along the surface normal, while increased working oxygen pressure produced non-epitaxial films with lattice elongation along the in-plane orientation. An effective electro-optic coefficient of ~21 pm/V was measured for the BTO films. Periodic BTO-STO superlattices were deposited with varying stacking periodicity between 27 and 1670 Å. Birefringence decreased with increasing stacking periodicity, due to relaxation of the lattice strain induced by the layer interfaces. The electro-optic response was found to reach a maximum at a specific stacking periodicity and it decreases with both increasing and decreasing individual layer thickness. The operation of a Mach-Zehnder waveguide intensity modulator based on the BTO-STO superlattice with effective electro-optic coefficient of 73 pm/V was also demonstrated.

KW - ferroelectrics

KW - thin film

KW - electro-optics

KW - superlattice

KW - PZT

KW - BaTiO3

KW - SrTiO3

M3 - Dissertation

SN - 978-951-38-7102-4

T3 - VTT Publications

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -