TEM Pictures of STM Tips
A few TEM studies of STM tips have been published in the literature.
Here are some TEM micrographs of STM tips we have taken.
These photos are useful reminders of why not every STM experiment yields reliable data.
Sharp STM tips can be easily made by cutting Pt/Ir (Platinum/Iridium) wire with a clean cutter.
The Pt/Ir tips do not oxidize as quickly as W (Tungsten) tips and can be kept for a longer time.
The overall shape of cut tips may not be well defined, but the end of the tips can be very sharp.
The followings images are TEM pictures of some STM tips.
The black objects represent the STM tips.
- TEM Picture of a cut STM Tip (Pt/Ir, 0.008" diameter). The image was
taken before the STM experiment
200 kV, Bar length = 5 micrometer
The cut tip is not well-shaped and sometimes it produces multiple tips.
But it can be very sharp at the end.
- TEM Picture of a cut STM Tip (Pt/Ir, 0.008" diameter). The image was
taken before the STM experiment
200 kV, Bar length = 50 nm
This image was taken from the second tip (the right-most tip) seen in the
above picture.
- TEM Picture of a cut STM Tip (Pt/Ir, 0.008" diameter). The image was
taken before the STM experiment
200 kV
Zoomed-in picture of the above area.
The end of cut tip is very sharp with a size less than 20 nm.
| Bar length = 20 nm |
Bar length = 20 nm |
Bar length = 10 nm |
 |
 |
 |
- TEM Picture of a cut STM Tip (Pt/Ir, 0.008" diameter). This is not the
same tip as seen in the above pictures.
The image was taken after the STM experiment
200 kV, Bar length = 1 micrometer
- TEM Picture of a cut STM Tip (Pt/Ir, 0.008" diameter). The image was
taken after an STM experiment
200 kV, Bar length = 200 nm
Zoomed-in picture of the above area.
The tip looks bent after an STM experiment.
- TEM Picture of an electrochemically etched STM Tip (Pt, 0.003" diameter).
The image was taken before an STM experiment
200 kV, Bar length = 10 nm
The etched tip is well-shaped, but not very
sharp at the end.
This is the end-form that is typically used in field
emission experiments.
TEM pictures were taken by Elton Graugnard and Takhee Lee (Sep. 1999).
Ron Reifenberger
Last modified: Fri Jul 19 11:29:35 EST 2002
