Pulsed DC reactive sputtering using a conducting target: A strong method to produce high-quality BiFeO3-based multiferroic thin films

Magnetoelectric multiferroic thin films are considered crucial for the development of next generation magnetic devices with low power consumption. This is due to the coexistence of ferroelectricity and ferromagnetism in the same phase, which enables its ability to control magnetization with the application of an electric field. Bismuth ferrite (BiFeO 3 ) based materials are one such promising contender, offering numerous advantages. The fabrication of these materials in the form of thin films is quite challenging because the crystal structure, including the oxygen atom, is complex. The fabrication method plays a crucial role in regulating both the structure and the ferroelectric and ferromagnetic behavior of these thin films. In this study, we have fabricated BiFeO 3 based thin films using pulsed DC reactive sputtering and compared their crystal structure, along with their magnetic and ferroelectric properties, with those of thin films fabricated using RF sputtering. Thin films fabricated using pulsed DC reactive sputtering reflect superior crystal structure as well as magnetic and insulating properties. The saturation magnetization in the case of pulsed DC reactive sputtering is found to be significantly higher (72 emu/cm³) than that of RF sputtering (48 emu/cm³). The leakage current has improved from 10 -5 A to 10 -7 A. Here, while fabricating high quality BiFeO 3 based thin films using pulsed DC reactive sputtering, careful consideration must be given to the sputtering target. If an insulating target for RF sputtering is used in this pulsed DC reactive sputtering, not only does arc discharge occur frequently, but also the thin film composition differs significantly from the target composition. Therefore, the target must be conductive. We found that BiFeO 3 based thin films fabricated using a specially designed target exhibit better conductivity, fewer arc discharges, and improved crystallinity of the thin film, resulting in a larger saturation magnetization and appreciable ferroelectric properties.