講演情報
[11a-N302-7]Structural, microstructural and electrical studies of (Bi,Na,Sr,Ba,Ca)TiO3 high entropy thin films
〇(D)Kishor KALITA1,2, Jumpei Mochizuki2, Shinya Kondo2, Mahesh Peddigari1, Tomoaki Yamada2 (1.IIT Hyderabad, 2.Nagoya Univ.)
キーワード：
Ferroelectric thin film、Energy storage capacitors
The advantages of dielectric thin film capacitors with high-power density, fast charge/discharge rate stimulated research into novel materials with enhanced energy storage characteristics. In this study, Lead-free (Bi,Na,Sr,Ba,Ca)TiO3 (BNSBCT) high-entropy perovskite oxide (HEPO) thin films were grown on SrRuO3/Pt/ZrO2/Si substrates using pulsed laser deposition at different substrate temperatures (25 oC (RT), 300 oC and 600 oC), and their structural, morphological, and electrical properties were systematically investigated. The BNSBCT HEPO ceramic target was fabricated using the spark plasma sintering technique. The HEPO films are grown with a KrF 248 nm laser, a substrate-target working distance of 45 mm, a laser repetition rate of 5 Hz, and a background oxygen pressure of 100 mTorr. The X-ray diffraction (XRD) results confirm the formation of the perovskite phase. The surface morphology and energy-dispersive X-ray spectroscopy are investigated to understand the volatile nature of Bi and Na in the thin films. The electric properties of the Pt/BNSBCT/SrRuO3/Pt/ZrO2/Si thin film capacitors were measured at room temperature. The room temperature dielectric response exhibited a strong dependence on substrate temperature with an enhanced dielectric constant and low dielectric loss at higher substrate temperature over a broad frequency range of 100 Hz to 20 MHz. To assess the energy-storage properties of the thin-film capacitors, polarization vs. electric-field (P-E) hysteresis loops are measured using a ferroelectric tester at 10kHz under different applied voltages. The optimization of post-annealing conditions is under investigation to achieve slim P-E hysteresis loops with high saturation polarization and breakdown strengths, which are essential for high energy storage density with enhanced efficiency.