Phase engineered gallium ferrite: a promising narrow bandgap, room-temperature ferroelectric. Issue 9 (6th April 2022) - Mukherjee, Somdutta
Abstract : Novel ferroelectric phase of gallium ferrite demonstrates narrow energy bandgap with large electronic contribution polarization, attractive for new generation optoelectronic and photovoltaic devices. Abstract : Narrow bandgap oxide ferroelectrics with large polarization are considered promising in novel optoelectronic and photovoltaic devices. In the present work, nanocrystalline gallium ferrite with polar, rhombohedral R 3 c symmetry is synthesized using the hydrothermal route. Structural characterization using X-ray diffraction, Raman spectroscopy, and electron microscopy confirm the formation of the rhombohedral R 3 c phase, with two different geometries and narrow size distribution. Electrical characterization corroborated by first-principles density functional theory-based calculations demonstrates room temperature ferroelectricity contributed mainly by triply charged gallium ions. The calculated spontaneous polarization is ∼20 μC cm −2 with a large electronic contribution. Optical characterization predicts a bandgap of ∼2.1 eV. Together with its narrow bandgap and the large contribution of electronic polarization, ferroelectric gallium ferrite could be an interesting system for novel photovoltaic and optoelectronic devices.