Effect of ZnO Interfacial Seed Layer in Sol–Gel Grown ZnMgO Ferroelectric

High remanent polarization observed in ferroelectric ZnMgO shows promise for ferroelectric memory devices made of low-cost, earth-abundant materials and is capable of a large memory window. To address the low performance of devices fabricated using low-cost sol–gel processing, an interfacial-structure-based approach to improve crystallinity in ZnMgO thin films was chosen. In this study, we demonstrate an increase of 182% in achievable remanent polarization coinciding with higher crystallinity and a larger ratio of ferroelectric wurtzite phase in sol–gel deposited Zn1–xMgxO (x = 0.35) films grown on an interfacial ZnO seed layer, through characterization of ferroelectric behavior via piezoresponse force microscopy and positive-up–negative-down measurements. Although the interfacial structure is not preserved after annealing, an improved remanent polarization of 0.699 μC/cm2 at a coercive field of 1 MV/cm is achieved in a sol–gel ZnMgO thin film through the addition of a ZnO buffer during processing.