Enhanced Photovoltaic Effects in Alkaline-earth and Rare-earth Metals Doping BiFeO3 Ceramics

• Main Authors: Zhe-Rui,Xu, 許哲睿
• Other Authors: Chi-Shun,Tu
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/42338892186458857805

碩士 === 輔仁大學 === 物理學系碩士班 === 103 === Structure, grain morphology, magnetization, photovoltaic effect, ferromagnetism, Raman spectroscopy, X-ray absorption spectroscopy, and transmission electron microscopy (TEM) have been systematically measured in A-site doped (Bi1-xAx)FeO3(A=Ca, Sr, Ba, La ; x=0.05, 0.1, 0.15) multiferroic ceramics. Raman spectra, XRD, and TEM reveal a rhombohedral R3c structure in BiFeO3. The A-site substitutions of Bi3+ by A-site (Sr2+ and Ba2+) can enhance ferromagnetic magnetization. The heterostructures of indium tin oxide (ITO) film/(Bi1-xAx)FeO3 ceramics/Au film exhibit significant photovoltaic (PV) effects under illumination of 405 nm. Open-circuit voltage (Voc) and short-circuit current density (Jsc) can be respectively described by using a p-n junction model. The maximal power-conversion efficiency in ITO/(Bi0.85La0.15)FeO2.925 (BFO-15%La)/Au can reach 0.19%, which is larger than 0.0025% in graphene/polycrystalline BFO/Pt (Appl. Phys. Lett. 99, 132904). The characteristic curves of current vs. voltage without illumination reveal a p-n heterojunction-like behavior in the interface between ITO film and (Bi1-xAx)FeO3 (A=Ca, Sr, Ba, La ; x=0.05, 0.1, 0.15) ceramics. We use the X-ray absorption spectroscopy to understand the enhanced ferromagnetism, which may associate with oxidation of Fe ion and the bond angle.