Orientation growth and electrical properties of ZnO/BaTiO3 heterostructures on silicon substrates by chemical solution deposition

Metal-ferroelectric-semiconductor (MFS) structures based on ZnO/BaTiO3 were fabricated by chemical solution deposition (CSD). The microstructure of the heterostructures was characterized by x-ray diffraction and atomic force microscopy. Both ZnO and BaTiO3 layers were found to be c-axial oriented on LaNiO3-coated silicon substrates. The morphology revealed good interface quality with root-mean-square values of about 10 nm. Compared with BaTiO3 ferroelectric thin films, the capacitance-voltage curves of Pt/ZnO/BaTiO3/LaNiO3 heterostructures exhibited a counterclockwise hysteresis loop for the MFS capacitor confirming the ferroelectric nature integrated with an n-type semiconductor. The memory windows increased and then reduced as the frequency changed from 100 kHz to 1 MHz, which can be explained by a frequency-dependent coercive field and electron injection behaviour. The current-voltage curves of ZnO/BaTiO3 heterostructure showed a good insulating characteristic. These results suggested that ZnO/BaTiO3 MFS heterostructures by CSD can be used for memory devices.