Investigation of nano-patterned PZT thin films by piezoresponse force microscopy

In this work, we describe an alternative lithography method for the fabrication of regular well-defined Pb(Zr,Ti)O₃ (PZT) nanodot arrays and the investigation of the local polarization and hysteresis properties of nano-patterned ferroelectric films. PZT films were produced by multi-target sputtering and patterned by nanosphere lithography. Therefore, a monolayer of well-ordered latex beads was assembled in a hexagonally close-packed array on a liquid-gas interface and deposited onto the PZT films. Both mask and film were then etched in a two-step process. By the first step, the size of the spheres was adjusted by low-pressure plasma etching, while secondly the PZT film was structured by ion-milling. The resulting nanostructures were investigated by piezoresponse force microscopy (PFM). The in-plane and out-of-plane polarization distribution was imaged. A reorganisation of the ferroelectric domains was observed depending on the structure and nanodot size. In addition, local hysteresis loops of single structures and domains were recorded.