Subsurface AFM

 

With the use of ultrasound waves one can 'look inside the sample' and obtain information on features that are buried inside a material, underneath the surface. The sound waves is scattered inside the sample and the signal of the scattered waves are picked up by means of an AFM cantilever. In a joint collaboration with dr. M.J. Rost at Leiden University, we develop tools to enable this Heterodyne Force Microscopy (HFM) technique.

Technique

The ultrasonic waves, with a frequency in the order of a few Megahertz, are sent through the sample with a piezo. Buried nano-particles or defects scatter the ultrasonic wave and generate a contrast pattern at the surface, which is possibly observable with an AFM cantilever. The AFM cantilever is used as an antenna to pick up the surface vibrations, which allows us to see the contrast pattern at the surface. Details on the contrast mechanism can be found here and here.

The main challenges are to eliminate any crosstalk of the (high frequency) signals in the AFM setup and to implement a method that allow sufficiently strong excitation of a cantilever in the MHz frequency range.

We combined our versatile high speed SPM Controller with the required HF electronic modules and with a newly designed 'HF cantilever holder'. This HF cantilever holder is compatible with a standard AFM scanner (Multimode). The details of the design of the HF cantilever holder and the way it is connected to the SPM controller are crucial in solving the two issues: electronic crosstalk and  excitation of a cantilever in the MHz frequency range.

We offer

We offer the HF cantilever holder as a 'ad-on' to an existing AFM system. This rather straightforward upgrade of existing AFM systems allowing researchers enter this new field of SPM and pioneer the new possibilities that sub-surface imaging offers. Contact us for details on the available holders and possibilities.

To exploit the full power of the HFM technique, we are developing a complete Subsurface AFM system. This system is optimized for working with the high frequency signals and offers a full solution for Subsurface AFM imaging. It provides researches a turn-key platform to extend AFM imaging with the possibility of 'looking inside samples'. Contact us for details on the system. We are open for collaborative projects.

 




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