Writing/Reading on Ferroelectric Materials

The initial surface was first imaged in non-contact mode without a bias voltage at the tip.
Imaging of the same surface area in non-contact mode without a bias voltage yields both dark and bright spots indicating the presence of positive and negative gradients.
This image was acquired with -1.5 V at the tip. The features appear black, due to a repulsive electrostatic force interaction.
The opposite contrast is observed here, where a positive bias of 1.5 V was applied to the cantilever tip.
EFM mode : The UHV AFM/STM was used in EFM mode (Electrostatic Force Microscopy) for writing and reading on LaTiO3,5 [1], a ferroelectric material. The conductive Si cantilever was prepared by ion sputtering. Using the nanostructuring routines of SCALA, the OMICRON logo was created by domain polarisation with the tip in contact with the surface and a voltage pulse of -8 V applied to the tip for 0.5 msec.


[1] : Sample and advice from Jean-Pierre Locquet, IBM Research Lab, Rüschlikon, are gratefully acknowledged

 
This result has been obtained with :
UHV AFM/STM

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