Electrical properties of ZnO-BaTiO_3-ZnO heterostructures with asymmetric interface charge distribution

摘要

We report on capacitance-voltage, current-voltage. Sawyer-Tower, and transient current switching measurements for a ZnO-BaTiO_3-ZnO heterostructure deposited on (001) silicon by using pulsed laser deposition. The triple-layer structure reveals asymmetric capacitance- and current-voltage hysteresis and cycling-voltage dependent Sawyer-Tower polarization drift. We explain our findings by coupling of the ferroelectric (BaTiO_3) and piezoelectric (ZnO) interface charges and parallel polarization orientation of the ZnO layers causing asymmetric space charge region formation under positive and negative bias. The transient current characteristics suggest use of this structure as nonvolatile memory device.