The effect of film thickness on the ferroelectric properties of sol-gel prepared lanthanum modified lead titanate thin films

Lanthanum modified lead titanate (PTL) thin films with a thickness ranging between 100 and 650 nm have been prepared by a sol-gel method. Hysteresis l oops have been measured in two sets of films.. thermally crystallized with 10 degrees Cmin(-1) and more than 500 degrees Cmin(-1). A thickness depende nce of the ferroelectric parameters has been found in both sets. This depen dence is related to the presence of a modified layer near the bottom electr ode, with a different origin in the two sets of films. In those treated wit h 10 degrees Cmin(-1), the layer is a Ti deficient one, most probably, with the perovskite structure but La deficient. In those treated with more than 500 degrees Cmin(-1) it is a layer that bears the ferroelectric-substrate interfacial stress. (C) 1999 Elsevier Science Limited. All rights reserved.