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CHARACTERIZATION

Atomic Force Microscopy | Dip Pen Nanolithography | Scanning Electron Microscopy

Dip Pen Nanolithography (DPN)

In a previous lab, Atomic Force Microscopy (AFM) was utilized to image the micron sized features of DVD's and/or CD's and the microcontact printed 2 micron lines of SAM's on a gold substrate. In this lab, an AFM tip will be used to write alkanethiol SAM patterns into gold substrates. You will practice writing a variety of shapes onto the surface and then image the pattern with Lateral Force Microscopy (LFM).

Modes of Operation for the DPN:

The three general types of DPN imaging are similar to those for AFM imaging: (1) contact mode, (2) tapping mode and (3) lateral force mode. Lateral force imaging-rather than topographical imaging-is generally the best way to scan completed DPN patterns because the system deposits ink in thin layers (as thin as one molecule) that would be hard to find topographically. LFM operates well under fast scan conditions. Quick imaging with the inky pen minimizes spurious ink deposition.

MATERIALS:

• DPN (PDF)
• SPM tips and Mount
• Alkane Thiol Solution
• Gold Substrate

PROCEDURE:

Using the skills you acquired in the previous lab, mount the gold substrate using double-sided tape and mount the thiol-covered probe tip. Adjust the AFM as instructed.

You will pattern dots (30-200 nm in diameter), lines, and other shapes of self-assembled monolayers (SAMs) on gold-coated silicon surfaces using DPN. Image your patterns by LFM.

QUESTIONS:

Tip Characterization

1. What type of cantilever did you use for DPN experiments and why?
2. Why are diving board cantilevers preferred over A shape cantilevers in DPN?
3. What sized patterns did you generate using DPN nanolithography?
4. Name four factors which determine the size of the nanopatterns during DPN writing?
5. Why is LFM mode imaging preferred in DPN over topography?

» More about PDN (PDF)