The effect of stresses on self-polarization of thin ferroelectric films

The effect of stresses, appearing due to a difference between the temperature coefficients of linear expansion of a substrate and ferroelectric film, on the self-polarization is discussed using thin films of lead zirconate-titanate PbZr_xTi_1?xO₃ (PZT) of different compositions as an example. It is assumed that the nature of self-polarization is connected with internal polarizing electric fields caused by the different density of charged surface states at the ferroelectric-layer interfaces, while tensile or compressive stresses are able only to change the polarization orientation, which causes the self-polarization to increase or decrease in magnitude. The problem of improving the efficiency of PZT films in infrared radiation detectors and memory devices is considered.