Polarization profiling of metal-ferroelectric-semiconductor structures by LIMM

In this work, the laser intensity modulation method (LIMM) is applied for the investigation of metal-ferroelectric-semiconductor structures. In particular, Pt/ferroelectric PZT (perovskite)/semi-conducting PZT (fluorite) was investigated. The pyroelectric coefficient profile was reconstructed using an simplified analytic solution of the LIMM problem and a thermal model consisting of up to eight different layers. Thermal expansion in (1 1 1) direction was calculated from the a-axis and c-axis values. The temperature coefficient of the dielectric constant was determined in the saturation range of the P–E hysteresis at various temperatures between 0 and 60 °C: (i) for the as deposited self-polarized films; (ii) from the slope of the hysteresis in the saturation range of the ferroelectric hysteresis; from (iii) from capacitance measurements of biased samples in the saturation range of the ferroelectric hysteresis.