Bellow valve (trap

1
FTS-deposition Chamber Configuration (all the
flanges are KF-25 unless indicated otherwise)
Liquid nitrogen trap
FTS deposition chamber with samples inside
(KF-40 full nipple)
Pumping direction
Bellow valve (trappump)
In-line filter with stainless steel wool trap
Bellow valve (FTS container)
Electrical feed-through for measurements (KF-40
flange with vacuum BNCs)
FTS container (1-2 cc)
Chemically resistive mechanical pump using
Fomblin oil
Inside glove box. (Note Ar glove box is not
necessary, if you work with single crystalline
organic materials like rubrene that have dense
hydrophobic surfaces, or if the atmospheric
humidity is low. It is recommended for work with
porous systems, such as polymer films or more
hydrophilic systems (e.g., graphene, CNTs) that
require annealing and transfer under Ar before
the FTS deposition).
Outside glove box
2
Optimized procedure for deposition of FTS
self-assembled monolayer on rubrene For the
original paper, please see M. F. Calhoun et
al., Nature Mater. 7, 84 (2008). 1. Place
samples in the FTS deposition chamber properly.
Connect the monitoring sample (with contacts and
wire leads) to the electrical feed-through
connectors and check the connectivity. Start the
program monitoring samples conductivity.
Assemble the rest of the system as shown in the
figure. 2. Make sure that the FTS container
valve is closed. Load an appropriate amount of
liquid FTS (Sigma Aldrich 448931) to the FTS
container a few drops for a short-time treatment
to achieve a partial coverage and somewhere
between 1/3 and 1/2 of the container for a long
treatment to get full coverage. Attach the
container to the deposition system properly as
shown in the figure. 3. Turn on the
mechanical pump and open the liquid nitrogen trap
pump valve (but not the FTS container valve).
Pump the deposition chamber for 40 minutes. 4.
Fill the cold trap with liquid nitrogen and wait
for another 10 minutes. 5. Slowly open the
FTS container valve and leave it open for 1 min,
while the mechanical pump is pumping the chamber
through the cold trap. This removes the small
amount of air trapped in the FTS container and
activates rapid evaporation of FTS molecules
filling the chamber with FTS fume. 6. After 1
min, close the liquid nitrogen trap pump valve.
7. Turn off the pump and disassemble the
liquid nitrogen trap. Leave all parts of the trap
under a well ventilated hood. Clean all parts
after they reach room temperature. 8. When FTS
deposition is done (which you monitor in-situ by
conductivity measurements), close the FTS
container valve. 9. Assemble the thoroughly
cleaned liquid nitrogen trap and connect it to
the system as shown in the figure. Turn on the
pump and wait for 1020 minutes, then add liquid
nitrogen and wait for another several
minutes. 10. Slowly open the liquid nitrogen
trap pump valve and pump the deposition chamber
for 30 minutes to remove the FTS fumes and FTS
accumulated on the inner walls of the chamber.
Keep sufficient amount of liquid nitrogen while
pumping (refill the trap when necessary). 11.
Close the liquid nitrogen trap pump valve. 12.
Turn off the pump and disassemble the liquid
nitrogen trap. Leave all parts of the trap under
a well ventilated fume hood. Clean all
parts again after they reach room
temperature. 13. Stop the electrical
measurements. Carefully open the FTS chamber to
the atmosphere (or Ar, if you work under Ar).
Remove samples. 14. Remove the FTS
container and clean it with acetone. 15.
Reassemble the deposition system, including the
FTS container and the cold trap. 16. Pump the
chamber for 10 minutes with both valves open.
Close both valves and turn off the pump. Store
the empty chamber in this closed condition
when not in use to slow down degradation of
parts.
3
Important notes 1. For high-quality
full-coverage FTS deposition, cleaning all the
parts on the right side of the PVC hose (see the
figure), including O-rings, chamber parts,
the FTS container valve and the electrical
feed-through connectors, is recommended each
time before deposition. Clean the PVC hose as
well if necessary. 2. Check the base pressure
of the clean, dry and fully assembled empty
chamber (w/o FTS or samples) regularly before
each treatment. FTS deposition failure is
usually due to a poor vacuum. In our experience,
the base pressure in a cleaned and fully
assembled chamber of our size is 7 - 8 ?10-4 Torr
after a 40-min pumping plus adding liquid
nitrogen to the trap. After a few uses, the
pressure becomes 1-2 ?10-3 Torr, which in our
experience is sufficient for a high-quality FTS
deposition. Condition of the pump oil and
the stainless steel wool trap should be checked
regularly. Do not use a vacuum gauge for
pressure measurements in-situ while doing
FTS deposition, because it may cause corrosion of
the gauge. 3. When not in use, keep the
deposition chamber fully assembled and under
vacuum.
?2D 1.210-5 S/?
Exposure to FTS vapor
Typical current as a function of time curve
recorded during the FTS deposition for a 2-probe
pristine rubrene sample. Voltage applied is V 1
V, distance between the contacts L 3 mm, width
of the crystal W 1 mm.
Same data on a semi-Log scale