Pyroelectric scanning probe microscopy: A method for local measurement of the pyroelectric effect in ferroelectric thin films

This work demonstrates a surface scanning method for the quantitative determination of the local pyroelectric coefficient in ferroelectric thin films. It allows generating a map of the pyroelectric response with very high spatial resolution. In domains of previously aligned dipole moments (achieved by tip-assisted poling) small heat fluctuations are achieved by laser diode excitation from the sample's bottom side thus inducing changes in the surface potential due to the pyroelectric effect. Simultaneously, the surface potential variations are detected by scanning surface potential microscopy thus forming the base for the pyroelectric coefficient map. The potential of the method is demonstrated on the basis of ferroelectric semicrystalline copolymer thin films yielding local maxima of the pyroelectric coefficients up to 40 mu C/m(2) K. Another promising feature is the ability to visualize screened polarization thus enabling in-depth profiling of polarization distributions and domain formation and to study the composition dependence of ferroelectric nanodomains.