Electroluminescence in BiFeO3 and the role of defects

Despite the existence of well-established reports on its photoluminescence spectrum, the phenomenon of electroluminescence in the BiFeO₃ (the multiferroic material par excellence) has not been previously reported. In this investigation, an electroluminescent effect is obtained in heterostructures fabricated with BiFeO3 microstructures on a p-type silicon substrate and transparent ITO contacts. These results are noteworthy in that the heterostructures exhibited the electroluminescent effect under both positive and negative bias, with a broad spectrum and diverse conduction mechanisms, including: Schottky and hopping conduction. In the presence of negative bias, the emission process necessitates the application of reduced voltages (initiating at -6V with a maximum emission intensity observed at −20V) and currents of approximately 100 mA. Additionally, the emission exhibits notable stability. When the device is subjected to positive bias, emission occurs at the edge of the device at higher voltages (starting at 30V) and lower currents of approximately 10 mA. This paper discusses the differences between the photoluminescence and electroluminescence spectra, their contributions to the broad emission spectrum, and the reasons why the emission is obtained with positive or negative bias.