McEuen Group Furnace Usage

1. Sign into blue log book
2. Check the regulators on the wall, if any are below 500PSI let Isaac know and he will order a new tank, if the tanks are below 250PSI do not use the system.
3. Remove end seals from previous user’s tube
4. Wipe down exterior of previous users tube with acetone
5. Put away previous user’s tube
6. Wipe down your quartz tube with acetone
7. If the tube is new label the tube with your name and flow direction
8. Connect end seals to your tube
   1. Pieces go onto the tube in the following order: large brass hex nut, plastic spacer, o-ring, stainless body w/ vacuum flange side out, o-ring, plastic spacer, small brass hex nut. Wipe all pieces down with acetone prior to install

1. Tighten the brass nuts making sure that the end of your tube is flush with the vacuum flange
2. As you tighten the nuts, twist the stainless body, this allows the o-rings to seat properly
3. Once the nuts are tight use the hand held vacuum pump to pump down the flanges (should be at 27 in. Hg on the gauges)
4. Slide your sample into the tube, if you use the push rod make sure to wipe it with acetone prior to use. Same applies for the quartz boat.
5. With the turbo pump off vent the turbo pump to atmosphere by pressing the vacuum valve button in the LabView program. The reason you want this at atmosphere is so that when you open the vacuum valve it doesn’t suck your sample into the pumping system. Leave the vacuum valve open.
6. Connect the vacuum flanges on each end.
7. Turn on the vacuum pump with the LabView program and allow to pump down to 6.0×10-5 Torr
8. Purge the gas lines by opening the argon, methane, and hydrogen valves in LabView. Allow to pump until it reaches a steady pressure then re-close the gas valves.
9. You are now ready to start your recipe. Make sure to never have the mass flow controllers on with the LabView valves closed
10. Once the furnace has cooled back to 200°C you can pressurize the system by turning off the vacuum pump, unhooking the left hand vacuum clamp, and introducing a 200sccm flow of argon.
11. Once the flange pops open unload your sample, turn off all mass flow controllers, and close all valves in LabView.

Note: The following sections have not been updated since the move.

Before using a McEuen Group furnace you must be trained to become an approved user. Please contact Melina Blees at mkb64@cornell.edu for more information. Only approved users may use the furnaces.

Becoming an approved user is essential for your safety and so that we are able to send out updates about changes to the furnace that may affect user operation of our equipment.

*NOTE [UNTIL FURTHER NOTICE]: The McEuen Group furnaces are currently undergoing renovations. Even if you have used the furnace before or are working with an approved user, please contact Melina Blees before using either furnace to receive training and/or become an approved user.

To book time on the Furnaces, please use the Furnace Scheduler.

Basic rules about booking time:

• People who have scheduled time get priority.
• Don't block off an entire 9am-5pm workday - leave some time in case someone needs to do a growth that day.

Please record your usage for either furnace in their respective handbooks. Include the following information:

• The date
• Your name
• The process you will be doing
• The tube you are using
• If necessary, include any general comments

If there is an issue contact someone in the McEuen Group immediately

The McEuen Group has two different furnaces; each is used for different processes and has different specifications.

Furnace 1 is used for carbon nanotube growth:

• Gasses include: Argon [10000sccm], Methane [10000sccm], Ethylene [10sccm], and Hydrogen [10000sccm].

Furnace 2 is used for graphene growth:

• Gasses include: Argon [500sscm], Methane [500sccm], and Hydrogen [200sccm].

• Vacuum Pump system – Reaches ~5 millitorr when no gasses are flowing.

• Flow rates listed are that of max flow rate of the flow controller. Remember that flow accuracy is related to max flow rate. Mass flow controllers are generally accurate to within 1% of their max flow rate.
• We have the ability to utilize Argon [60sccm] bubbled through water if necessary. Do not attempt to do this yourself. Contact Alex at arr68@cornell.edu. [Note: this flow controller is a bit finicky, so it may not be very accurate.]

The current furnace set up requires you to use a program to run your growth. Rather than setting your temperatures and pressing the set button (and doing that for all of the temperature changes during a growth) you must now set a program that will go through all of this for you. To set your program, hold the SET/ENT button for 3 seconds until the display reads “PrG” for program. Once this screen appears, use the up button to change the number from 0 to 1 and then press the SET/ENT button; this brings you to the parameters for Program #1. At this point, press the SET/ENT button until the display reads “SP1” meaning “Set point 1.” Now, use the up and down buttons to set the first temperature for your growth. Once it is set, press the SET/ENT button again, the display will read “tn1.” This is the time parameter for Set Point 1. This value will dictate how long the furnace takes to reach Set Point 1. Entering a value of 0 will cause the furnace to go to SP1 as fast as it can, without overshooting. After you set this first time value, you can then set many more set points (and respective times) that correspond with your growth. Access these parameters by pressing SET/ENT after you have set a previous set point and temperature pair (i.e. Set point and time 3 will not appear if Set point and time 2 are not set). When you are satisfied with your settings, make the last set point/time pair 0 and off, respectively (off is located below 0). Now you can hold down the SET/ENT button again to save your program and return to the original temperature display. Once your program is set up hold the RUN button (also the down button) to start your program – you will hear the relay. This furnace will now run through the program you set and will automatically switch off the relay when your program is finished. If at any time you need to terminate your program early, hold the RESET button (also the up button) to switch off the relay and turn the furnace off.

• The furnace has an offset on it to compensate for the position of the thermocouple. At growth temperatures, the furnace will be accurate in its temperature display. This value corresponds to the temperature inside the quartz tube at the center of the furnace.
• When setting the times, 0.00 is in the format of hr.minutes. e.g. 1.27 would be one hour and twenty seven minutes.
• The controller only supports one program – Program #1. Do not attempt to set other programs.
• The furnace has a 2 degree window in which it will find a temperature value correct and move to the next step in a program. For example, you might find that a program that says to sit at 850 for 1 hour actually only lasts 59 minutes if you start a timer exactly when the furnace reaches 850. This is because at 848 degrees (because of the 2 degree window), the furnace will register the previous step as complete and start counting the 1 hour. If you absolutely need this changed, please contact someone in the McEuen group.
• You must control your gas flow manually! Be prompt, your program won’t wait for you.
• Do not assume your program has remained the same since your last furnace use. There are multiple furnace users, check to make sure the program you wish to use is entered before running the furnace.

This program does this following – Go from off (room temp) to 500 degrees as fast as possible; Go from 500 degrees to 600 degrees over 10 minutes; go from 600 to 900 as fast as possible; Hold 900 for 5 minutes for growth step A; Hold 900 for 1 hour and 20 minutes for growth step B; end of growth.

If you have any questions or concerns related to the furnaces please find a McEuen group member before using the furnace or contact Alex at arr68@cornell.edu.

Thank you.

There are two major adjustments that need to be made.

• 1. Set the gas calibration factor
• 2. Set the flow range.

These adjustments need to be made for each channel and can be done using the mass flow controller interface. Note that each channel has a certain gas and a certain flow controller (which defines the range) associated with it.

• This means you must know what channel controls what gas with which flow controller.
• This also means that many of the values for each channel will be different.