Evaluation of ferroelectricity in a distorted wurtzite-type structure of Sc-doped LiGaO.

Since the discovery of ferroelectricity in a wurtzite-type structure, this structural type has gathered much attention as a next-generation ferroelectric material due to its high polarization value combined with its high breakdown strength. However, the main targets of wurtzite-type ferroelectrics have been limited thus far to simple nitride/oxide compounds. The investigation of new ferroelectric materials with wurtzite-type structures is important for understanding ferroelectricity in such structures. We therefore focus on β-LiGaO in this study. Although AlN and ZnO possess well-known wurtzite-type structures (6), β-LiGaO has a distorted wurtzite-type structure (2), and there are no reports of ferroelectricity in LiGaO. In this study, we have revealed that LiGaO exhibits relatively high barrier height energy for polarization switching, however, Sc doping effectively reduces that energy. Then, we conducted thin film preparation and evaluation for Sc-doped LiGaO to observe its ferroelectric properties. We successfully observed ferroelectric behavior by using piezoresponse force microscopy measurements for LiGaScO/SrRuO/(111)SrTiO.