Evaluation of ferroelectricity in a distorted wurtzite-type structure of Sc-doped LiGaO 2 .

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 2 in this study. Although AlN and ZnO possess well-known wurtzite-type structures ( P 6 3 mc ), β-LiGaO 2 has a distorted wurtzite-type structure ( Pna 2 1 ), and there are no reports of ferroelectricity in LiGaO 2 . In this study, we have revealed that LiGaO 2 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 2 to observe its ferroelectric properties. We successfully observed ferroelectric behavior by using piezoresponse force microscopy measurements for LiGa 0.8 Sc 0.2 O 2 /SrRuO 3 /(111)SrTiO 3 .