Ferroelectric domain switching investigation of BiFeO3 thin film on Pt/Ti/SiO2/Si (1 1 1) substrate

The ferroelectric domain structure and polarization switching of the BiFeO3 thin film deposited on Pt/Ti/SiO2/Si(1 1 1) substrate using rf magnetron sputtering technique were studied by piezoelectric force microscopy. The initial domains were dominanted by the upward polarization state in our sample. The positive and negative dc biases switched the ferroelectric domains downward and upward, respectively; and the upward switching was more difficult than the downward one, demonstrating an unsymmetric ferroelectric hysteresis loop in our sample. The electric field dependent experiments were carried out to understand the evolution of the domain switching, and the obvious change in phase image was obtained only when poling at +10 V, which implied the poling was performed close to the coercive field. The uncomplete domain switching was attributed to the unsufficient bisas, the impurity defect and the strain conditions as the result of ferroelastic domain displacement/creation.