The aim of this study is to produce Nb doped PZT thin films and then investigate the effects of Nb+5 ion on the structural, dielectric and ferroelectric properties. Niobium (Nb) doped lead zirconate titanate thin films (PNZT) were produced by solution deposition with nominal compositions, Pb(1-0.5x)(Zr0.53Ti0.47)1-xNbxO3 where x = 0.00 - 0.07. Single and multi-layered films were deposited onto (111)-Pt/Ti/SiO2/Si-(100) substrates by spin coating. PZT compositions near the morphotropic phase boundary (MPB) was chosen because excellent ferroelectric and dielectric properties were achieved in this area. The effects of sintering temperature, sintering time, variation of thickness in the films and change of niobium content were investigated with regard to phase development, microstructure, and ferroelectric and dielectric characteristics. The best results were obtained in double layered films (390 nm) which were sintered at 600 &deg / C for 1 h. Grain size of the films decreases with increasing Nb content except for 1 at % Nb doped films. The average grain size of 1 at % Nb doped thin films was calculated as 130 nm by using FESEM. Optimum doping level was found in 1 at % Nb doped films. For 1 at % Nb doped [Pb0.995(Zr0.53Ti0.47)0.99Nb0.01O3] films, remnant polarization (Pr) of 35.75 &amp / #956 / C/cm2 and coercive field (Ec) of 75.65 kV/cm have been obtained. The maximum dielectric constant was achieved in 1 at % Nb doped films which was 689. Tangent loss values were found between 2-4 % and these values were independent of Nb concentrations. Ferroelectric and dielectric properties were decreased at higher Nb doping levels because of the changes in the grain size, distortion of the crystal structure and pinning of the domains.

Abstract In this work, phase structure and the surface morphology effects on the optical properties of nonlinear active nanocrystalline PZT thin films, with the high refractive index (n ≈ 2.5), were studied. A preliminary thickness-temperature map of the majority phase was presented, showing the dependence of room temperature deposited films thickness and post-annealing temperature on the crystallization and surface morphology. Changes in structural phase and surface morphology were found to define the optical properties of the films. The optical absorption edge shifted to shorter wavelengths with decreasing film thickness and post-annealing temperature, which led to an increase in band gap energies with ΔEg ≈ 0.55eV. Structural phase evolution induced surface effects caused the definite diffuse elements in the transmission spectra of the films. Low and evenly distributed scattering amplitudes in k-space were seen for single-phase oriented films with non-textured surfaces and led to low diffuse transmission values with TD ≈ 5%. Confined and increased scattering amplitudes in k-space were seen for films with phase co-existence, leading to microstructure-induced textured surfaces and increased diffuse transmission values with TD ≈ 50%. Diffuse transmission properties of the films were also calculated from surface profile data, using scalar scattering theory. The results showed very good agreement with the experimentally defined values. The difference between modelled and measured values was 3.8% at the maximum. Also changes in the surface morphology and crystal orientation were found to modulate the full width at half maximum Δβ values of the TE0 optical mode, indicating a strong dependence on the surface scattering process. Sharp optical mode widths Δβ ≈ 0.0048 and Δβ ≈ 0.0006, for single-phase oriented and amorphous-like films, respectively, were found. / Tiivistelmä Tässä työssä tutkittiin nanokiteisten korkean taitekertoimen (n ≈ 2.5) omaavien PZT ohutkalvojen optisten ominaisuuksien riippuvuutta ohutkalvon faasirakenteesta ja pinnan morfologiasta. Rakenneanalyysien perusteella muodostettiin paksuus-lämpötila faasikartta havainnollistamaan jälkihehkutuslämpötilan ja kalvon paksuuden vaikutuksia huoneenlämpötilassa pulssilaserkasvatusmenetelmällä kasvatettujen ohutkalvojen faasirakenteen ja pinnan morfologian muokkautumiseen. Muutokset kalvon faasirakenteessa ja pinnan morfologiassa määrittivät täysin kalvon optiset ominaisuudet siten, että optinen absorptioreuna siirtyi alemmille aallonpituuksille kalvon paksuuden ja jälkihehkutuslämpötilan pienentyessä, aiheuttaen energiaraon kasvun (ΔEg ≈ 0.55 eV). Faasirakenteen indusoiman pinnan morfologian muokkautuminen määritteli myös ohutkalvon sirontaspektrin yksityiskohdat aaltolukuavaruudessa. Tasaisesti jakautunut pienen amplitudin omaava sirontaspektri ja alhainen diffuusi sironta (TD ≈ 5 %) oli ominaista yksifaasisille, voimakkaasti orientoituneille ohutkalvoille, kun taas alhaisille aaltolukuarvoille rajoittunut korkean amplitudin omaava sirontaspektri ja lisääntynyt diffuusi sironta (TD ≈ 50 %) oli ominaista kaksifaasisille ohutkalvoille. Tutkittujen ohutkalvojen sirontaspektrin diffuusi komponentti laskettiin myös käyttäen skalaaria sirontateoriaa. Ero laskettujen ja mitattujen arvojen välillä oli maksimissaan 3.8 %. Muutokset ohutkalvojen pinnan morfologiassa ja faasirakenteessa havaittiin myös moduloivan optisen TE0 moodin puoliarvoleveyttä. Alhaisimmat pouoliarvoleveydet havaittiin yksifaasisilla (Δβ ≈ 0.0048) ja amorfisenkaltaisilla ohutkalvoilla (Δβ ≈ 0.0006).