講演情報
[10a-B31-2]Single-Domain BiFeO3 Thin Films Grown by Low-Temperature Hydrothermal Epitaxy for Ferroelectric Photovoltaic Applications
〇(P)Kathirvel Aruchamy1,2, Seiji Nakashima2, Ai I Osaka2, Hironori Fujisawa2, Takuro Kubota3, Hiroshi Uchida3, Hiroshi Funakubo4 (1.JSPS Fellow, 2.Univ. of Hyogo, 3.Sophia Univ., 4.Tokyo Inst. of Tech.)
キーワード：
Ferroelectrics Solar cell、Single domain、Low-temperature growth
Bulk photovoltaic effect (BPVEs) in ferroelectric materials have attracted the considerable attention because they can generate open-circuit voltage beyond the bandgap limit. Unlike conventional p-n junctional solar cells, ferroelectric materials enable polarization driven photocarrier separation without the need for a depletion region. Among them, lead-free BiFeO3 (BFO) is a promising candidate for ferroelectric photovoltaic applications owing to its large spontaneous polarization (~100 µC/cm2) and narrow optical bandgap (~2.2 eV). However, high-quality epitaxial BFO thin films are typically fabricated using high-temperature vacuum-based techniques, such as PLD and MBE, which are energy-intensive and costly.
In this work, high-quality single domain epitaxial BFO thin films were successfully grown by a low-temperature hydrothermal method [1] on SRO-buffered vicinal SrTiO3 (001) substrates with a 4° miscut toward the [110] direction. XRD confirmed highly c-axis-oriented rhombohedral BFO films with clear (00l) reflections. SEM images showed clear well-defined terrace-like surface morphologies originating from the vicinal substrate, while AFM analyses showed smooth and uniform surfaces. PFM analysis confirmed the formation of single-domain BFO film. The use of vicinal substrate promotes step-flow growth and reduces the formation of polarization variants, enabling domain engineering during the growth. The noticed terrace morphology and single-domain structure signify the effective coupling between vicinal surface steps and ferroelectric domain growth. Further structural and electrical characterization were performed to elucidate the epitaxial growth behavior and ferroelectric properties of the films. The present results indicate that hydrothermal growth is an energy-efficient and cost-effective route for obtaining single-domain BFO thin films suitable for ferroelectric photovoltaic applications.
In this work, high-quality single domain epitaxial BFO thin films were successfully grown by a low-temperature hydrothermal method [1] on SRO-buffered vicinal SrTiO3 (001) substrates with a 4° miscut toward the [110] direction. XRD confirmed highly c-axis-oriented rhombohedral BFO films with clear (00l) reflections. SEM images showed clear well-defined terrace-like surface morphologies originating from the vicinal substrate, while AFM analyses showed smooth and uniform surfaces. PFM analysis confirmed the formation of single-domain BFO film. The use of vicinal substrate promotes step-flow growth and reduces the formation of polarization variants, enabling domain engineering during the growth. The noticed terrace morphology and single-domain structure signify the effective coupling between vicinal surface steps and ferroelectric domain growth. Further structural and electrical characterization were performed to elucidate the epitaxial growth behavior and ferroelectric properties of the films. The present results indicate that hydrothermal growth is an energy-efficient and cost-effective route for obtaining single-domain BFO thin films suitable for ferroelectric photovoltaic applications.