Current transient versus time investigation of charged defect motion in sandwich-structured La-modified Bi2Ti4O11 films for large charge storage

Current transient versus time (I–t) measurements at various dc biases were performed on La-modified Bi2Ti4O11 films composed of TiO2 and Bi4Ti3O12 double phases. An inhomogeneous external field distribution within the two phases causes a series of discrete current peaks in the I–t curves. At reversed dc biases, injected charges in the films can be released at voltages higher than a threshold voltage. The discharged capacitors are recharged automatically with a prolonged waiting time after removal of a dc bias. This is shown to originate from the charged defect motion confined within TiO2 layers.