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--- nanotube_growth [2019/09/09 21:12] – created ethanminot
+++ nanotube_growth [2022/08/09 16:33] (current) – dublin
@@ Line 8: / Line 8: @@
-===== "Paint-on" catalysts =====
+===== Paint-on catalysts =====
-We have tried at least four different iron-based catalysts that are suspended in a solvent. Even more variations exist in the literature. The Alumina supported catalyst is tried and true:
+We have tried at least four different iron-based catalysts that are suspended in a solvent. Even more variations exist in the literature. The alumina supported catalyst is tried and true:
-|{{:cnt_02_contrast_500.jpg?350|}}|**Figure:** SEM image of CNTs growing from [[purchasing_supplies|alumina]] supported catalyst. Scale bar is 200 nm. The advantage of alumina supported catalyst is the high surface area of the alumina. The high surface area leads to more nanotube nucleation sites. One disadvantage is that alumina nanoparticles, together with sticky nanotube grass, stick to the AFM tip during imaging (it is best to avoid imaging directly over the alumina!). A second disadvantage is that the diameter distribution of CNTs tends to be broad.|
+|{{:cnt_02_contrast_500.jpg?450|}}|**Figure:** SEM image of CNTs growing from [[purchasing_supplies|alumina]] supported catalyst. Scale bar is 200 nm. The advantage of alumina supported catalyst is the high surface area of the alumina. The high surface area leads to more nanotube nucleation sites. One disadvantage is that alumina nanoparticles, together with sticky nanotube grass, stick to the AFM tip during imaging (it is best to avoid imaging directly over the alumina!). A second disadvantage is that the diameter distribution of CNTs tends to be broad.|
+|{{::catalyst.png?450|}}|This image comes from Ethan Minot's PhD thesis (Fig. 3.2). The alumina supported catalyst is patterned in a 4 x 4 micron square. Hundreds of CNT grow inside the 4 x 4 square, making it look like a bird's nest.|
-  - [[purchasing_supplies|Alumina]] supported catalyst. The original recipe for this catalyst was published in Nature in 1998 (Kong et al.). Kong used 45 mL of IPA instead of 45 mL of DI water, but IPA is not compatible with photoresist patterning (IPA is only compatible with ebeam resist). The original recipe from Kong et al. also has an additional baking step after solution deposition. Here is the updated recipe developed in the McEuen group. The Dekker group still uses the IPA solvent:
+  - [[purchasing_supplies|Alumina]] supported catalyst. The original recipe for this catalyst was published in Nature in 1998 ([[https://www.nature.com/articles/27632|Kong et al.]]). Kong used methanol as the liquid instead of DI water, but methanol is not compatible with photoresist patterning (methanol is compatible with ebeam resist). Other groups (for example, Cees Dekker's group) have used isopropanol as the liquid. I don't know if the choice of liquid makes a difference. The original recipe from Kong et al. also has an additional baking step after solution deposition which many groups now skip. Here is a water-based recipe (compatible with photoresist) that was developed in the McEuen group:
     *60 mg Fe(NO3)3•9H2O * **see the suggestion below**
     *15 mg MoO2(acac)2 * **see the suggestion below**
@@ Line 40: / Line 41: @@
 === Recipes ===
-*UPDATED 05/28/2012 by Heather*
+*UPDATED 2022 by Dublin
-(Click here for [[other recipes]])
+(Click here for [[other recipes]]) and [[old_recipes]]
-  *Check that the gas cylinders are all on and have plenty of gas (the pressure inside a full cylinders is about 1500 psi).
+==== 1" Furnace growth ====
-  *Open furnace lid. Open growth tube carefully.  Place sample within growth tube.  Use the quartz push rod to slide the sample to the center of the furnace.
-  *Close growth tube. Establish vacuum seals to the quartz tube.  Close furnace lid.
-  *Set purge parameters in automated program.
-  *Make sure furnace and power supplies are on.
-  *If you are doing alcohol growth add ice and water to the beakers that the bubblers are in.
-  *Press the start button on the automated growth display panel.
-  *Allow system to cycle.
-  *Set growth parameters in automated growth program.
-  *Press the start button on the automated growth display panel.
-  *Allow system to cycle.
-  *At 400C, safe to open furnace lid (speeds up cooling process)
-  *At 200C, safe to handle growth tube and retrieve sample.
-    * **Purge Parameters**
+__**Startup/Loading chips**__
-    -Anneal temperature = 100C
-    -Anneal time = 10 minutes
-    -Anneal gases (if alcohol growth is planned) = 0.45 SLM Hydrogen, 0.30 SLM Methanol, 0.15 SLM Ethanol, and 0.50 SLM Argon
-    -Anneal gases (if other recipe is planned) = growth gases and flow rates, and 0.5 SLM Argon
-    -Growth temperature = 0C
-    -Growth time = 0 minutes
-    -Growth gases = 0 and uncheck all gases (check “neither”)
-    * **Alcohol Growth Parameters**
-    -Anneal temperature = 800C
-    -Anneal time = 15 minutes
-    -Anneal gas = Atmosphere
-    -Growth temperature = 900C
-    -Growth time = 15 minutes
-    -Growth gases = 0.45 SLM Hydrogen, 0.30 SLM Methanol, and 0.15 SLM Ethanol
-    * **Methane Growth Parameters** (suggested by McEuen group)
-    -Anneal temperature = 550C
-    -Anneal time = 5 minutes
-    -Anneal gas = Atmosphere
-    -Growth temperature = 825C
-    -Growth time = 60 miniutes
-    -Growth gases = 1.9 SLM Methane, 0.3 SLM Hydrogen
+  - Keep chips ready for growth in furnace
+  - PNF are for Utah
+  - PNF - 2 micron trench
+  - PNR - 2.6 micron trench
+  - To pressurize:
+  - Connect hand pump to nipple
+  - Black button releases pressure
+  - Pump up to 25 in Hg
+Ethanol/methanol levels: Use around half as much Methanol as Ethanol. (In my experience, a 1:1 ratio produces more multi-tube sites and shorts, so this ratio is important. - Dublin)
+  - Fill out logbook
+  - Always run purge
+  - STD growth
+  - Humidity
+  - Turn on Dehumidifier
+  - Humidity should be around 30%
+  - Check end cap is secure
+  - Check Ar and H tanks
+  - 20PSI on both
+  - Lose around 5psi of argon tank pressure per hour of flowing
+  - Load in chips. (I have successfully grown 3 at a time, which is all you can fit on the boat. - Dublin)
+  - Unscrew the end part
+  - Careful not to drop it
+  - Attach magnet to end of tray and slide in chip
+  - Reattach end part
+  - Current tube 2022:  “Tristan”
+__**Growth Process**__
+Input purge parameters:
+Anneal:
+  * 30 C
+  * 3 min
+  * Hydrogen: 0.45 SLM
+  * Argon: 1SLM
+Transition:
+  * 0 min (no transition)
+Growth:
+  * 30 C
+  * 3 min
+  * Hydrogen 0.45 SLM
+  * Methanol 0.3 SLM
+  * Ethanol 0.15 SLM
+  - Set timer for 5 min and start purge. Will go through anneal and “growth” stages at 30 C
+  * When changing parameters, give the program a few seconds to get it
+  * After purge finishes, reinitialize parameters
+  * Wait until all flow rates show zero
+Growth Parameters:
+Anneal:
+  * 800 C
+  * Hydrogen: 0.45 SLM
+  * 1 min
+Transition:
+  * 0 min ramp time
+Growth:
+  * 800 C
+  * 5 min
+  * Hydrogen 0.45 SLM
+  * Methanol 0.3 SLM
+  * Ethanol 0.15 SLM
+  - Start growth and set a timer for 14:30. When the furnace reaches 798 C, slowly and deliberately slide in tubes
+  - Once anneal phase begins, set timer for 4:30 min
+  - To check if it’s working: Ethanol and methanol are bubbling.
+  - When PID controller clicks off (growth is finished):
+  - Pull chip to rim of insulating chamber and allow to sit until 790 C
+  - Pull chip fully out
+  - When temp is 500 C, open lid
+  - When temp is 200 C or lower, pull out chip
+  - The program flows argon before 200C
+  - Close lid
+  - Unscrew end connector
+  - Drag magnet as far to the left as possible
+  - Grab back end of sled and pull chip straight out
+  - Grab in center of rod
+  - Keep the chip level! It’s not connected
+  - Place chip on beta wipe
+  - Hold rod while grabbing chip and place chip in holder
+  - Store rod in quartz tube, cap it up
+  - Screw end cap back on and seal tube
+  - Once chamber is cooled back down to room temperature, ready for another growth
-=== Growth Success Table ===
-^Catalyst ^Evaporated Stain ^ Rinsed Stain ^ Tape ^ Photoresist ^Ink Jet ^Spin Coating ^Sputtered^
-| CuCl2/PVP | | | | | | N| |
-| CuCl2| N | N | | | | | |
-| FeMo| Y,N| N| | | | | |
-|Ferritin |Y,Y | N | | Y | | N | |
-| FeMo + alumina| Y| Y| | Y| | Y| |
-| Sputtered Iron| | | | | | |Y|
 ===== 4" Furnace growth =====