BiMg2/3Nb1/3O3-based thin films from Chemical Solution Deposition: A study on the influence of the process parameters on the structure and the electrical properties

Theresa Gindel

Research output: ThesisMaster's Thesis

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Abstract

Enhancing the energy storage properties of lead-free dielectric capacitors is a key focus in today's microelectronic industry. This objective is gaining importance in the quest to develop lead-free devices that align with lead-based property standards while minimizing the toxicity associated with processing and the end products. BiMg2/3Nb1/3O3-based thin films show promising energy storage properties due to the disruption of the long-range ferroelectric order. The relaxor-like behavior results in slimmer polarization vs. electric field hysteresis loops (PE loops) compared to ferroelectrics and leading to a significant reduction in energy losses while maintaining a high permittivity. The use of thin film technology, as opposed to bulk ceramics, is a crucial step in the miniaturization of devices. In addition, this technique increases energy density and increases breakdown fields by improving microstructure and promoting texture.
In this thesis, thin films based on (1-x)Bi(Mg2/3Nb1/3)O3–xBi0.5Na0.5TiO3 (BMN-BNT, x = 0.85) and (1-x)Bi(Mg2/3Nb1/3)O3–xNaNbO3 (BMN-NN, x = 0.78) systems were produced by chemical solution deposition (CSD) on Pt/TiO2/SiO2/Si substrates. All films have been successfully synthesized and the influence of different heating rates and crystallization temperatures on the microstructure and electrical properties have been investigated and characterized. Characterization analysis was carried out using Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy-Dispersive X-ray (EDX) analysis. Electrical measurements (PE loops) were conducted to evaluate the energy storage properties and to gain insights into the temperature-dependent response and cyclic fatigue behavior of the various films. Both thin film systems show a phase pure and highly crystalline perovskite structure in both XRD and Raman spectroscopy. The BMN-BNT composition showed the most promising energy storage properties (Wrec ~ 20 J/cm3 and 69% efficiency), coupled with excellent thermal stability up to 140°C. However, superior cyclic fatigue stability, extending up to 10^6 unipolar cycles, and low leakage currents were observed for the BMN-NN system. In a broader context, it can be confirmed that varying process parameters significantly impact both the microstructure and the electrical properties of the two material systems. The complex interplay between structural characteristics and electrical behavior underscores the need of thorough exploration of processing conditions in achieving tailored material properties.
Translated title of the contributionBiMg2/3Nb1/3O3-basierte Dünnschichten aus der chemischen Lösungsabscheidung: Eine Studie über den Einfluss der Prozessparameter auf die Struktur und die elektrischen Eigenschaften
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Deluca, Marco, Co-Supervisor (internal)
  • Bermejo, Raul, Supervisor (internal)
Award date22 Mar 2024
DOIs
Publication statusPublished - 2024

Bibliographical note

no embargo

Keywords

  • BMN
  • Thin films
  • Chemical Solution Deposition
  • Process parameters

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