Simon Bühlmann

Accessing the Nanoscale in Ferroelectrics: Fabrication, Analysis and Modelling of Patterned and Self- Assembled Ferroelectric Nanostructures Simon Bühlmann

The continuous downscaling in microelectronic circuits faces various challenges that affect fabrication, material properties and characterization techniques. The present work illustrates this for the field of ferroelectrics. Two routes for the fabrication of ferroelectric nanostructures are presented. In a subtractive route, a ferroelectric thin film is the starting point from which ferroelectric nanostructures are cut out. In an additive route, the ferroelectric matter is deposited onto a surface with predefined affinity seed-spots. In this non-destructive method, ferroelectric crystals are formed on the seeds but not elsewhere. A modified atomic force microscope is used to characterize the quality of the ferroelectric properties. A dramatic increase of the piezoelectric response was discovered in nanostructures when they reach a certain geometrical aspect ratio and on thin films after local training with the tip. The size-limit of ferroelectricity and the physics of nucleation are elaborated in more theoretical detail with respect to findings of the present work. Finally, an extensive literature survey is given.