McEuen Recipes

• Anneal ST-cut quartz substrate in air for 8 hours at 900C.
• Electron beam evaporation of Fe as a catalyst.
• Anneal Fe in air at 550C. (10 min?)
• Purge with H2 for 5 min at 900C. (0.3 SLM?)
• Growth gas for 1 hour:
  1. 0.3 SLM H2
  2. 1.9 SLM CH4

• Anneal chip: Heat in 1 SLM Ar and 0.5 SLM H2 to 700 C for 5-10 min
• Stop H2, heat to 900 C
• Stop Ar, flow 5 SLM CH4 for 10 min
• Cool in 1 SLM Ar (open furnace lid when temperature drops to 600C)

For us, successful with alumina, unsuccessful with ferratin.

• Heat in 1 SLM Ar to 900 C
• Without delay, switch gases in the following order
  1. H2 from 0 to 0.1 SLM
  2. Ar from 1 to 0 SLM
  3. CH4 from 0 to 1.5 SLM
• Wait 10 minutes, then
  1. Turn off CH4
  2. Turn off furnace
  3. Switch Ar to 1 SLM
• Open furnace lid when temperature drops to 600C

For us, successful with alumina, unsuccessful with ferratin.

A mixture of Ar and H2 is bubbled through liquid ethanol. This idea was first suggested by Prof. Liu's lab. The ethanol is kept in a bowl of ice water to achieve the ideal vapor pressure. The Columbia group now uses Ethanol growth for making 100 micron up to 4 mm long nanotubes.

Long nanotube growth results in significant bundling of nanotubes. This is not surprising, since millimeter long hairs will tend to get tangled with each other as they flutter around in the gas flow. One solution is to use a very dilute scattering of catalyst on the surface, perhaps only 100 nanoparticles on a 1 cm chip. Ideally, each catalyst nanoparticle will be active and produce a long tube.

Ethylene growth works at lower growth temperatures. Other C2H4 (ethylene) recipes do not call for such large ethylene flow.

• Heat to 700 C with 1 SLM Ar
• Anneal with 0.15 SLM Ar and 0.1 SLM H2 for 15 min
• Add additional 5.5 SCCM C2H4 for 6 min
• Cool in 1 SLM Ar

This recipe was popular for a few years, since it was capable of growing 4 cm long nanotubes. The recipe involves moving the quartz tube within the furnace when the furnace is 900 C. Recently, the Columbia group has found that moving the quartz tube is not necessary to grow long nanotubes. This version of the recipe comes from the McEuen group.

• Start with tube far to the right, insert chips so they are in the center of the heating coils, and mark on the furnace tube just outside the furnace on the left edge
• Start with chips outside
• Heat to 1015-1040 C in 0.8 SLM Ar, with or without 0.2 SLM H2 (5-6 min). If flow rate is too fast the furnace will struggle to reach high temperatures.
• Add 0.2 SLM H2, 0.8 SLM CH4, 5.5 SCCM C2H4, wait 2 min
• Turn off Ar, set T to 915-930 C, pull in tube so chips are in center, grow 10 min
• Cool in 0.8 SLM Ar and maybe 0.2 SLM H2 (~30 min): open furnace at 500 C, remove chips at 100 C

CAUTION: When making gas flow conversions (mm ↔ SLM) for a new recipe DO NOT assume the conversion is linear and use an old recipe to get the curve in the right place. In the furnace's folder there are conversion graphs (and they are not linear); use those to make conversions.

• Ultralong, well-aligned single-walled carbon nanotube architectures on surfaces, S. Huang, 2003

• Growth Mechanism of Oriented Long Single Walled Carbon Nanotubes Using 'Fast-Heating' Chemical Vapor Deposition Process, S. Huang, 2004
  1. Recipe: various catalysts (Fe+Mo, Fe, Fe+Pt, clusters w/ Fe+Mo), various feedstock (CO+H2, other alcohols and hydrocarbons), 900 oC fast heating for 20 min.

• Long and Oriented Single-Walled Carbon Nanotubes Grown by Ethanol Chemical Vapor Deposition, L. Huang, 2004
  1. Recipe: CoMo catalyst, .350 SLM Ar + .005 SLM H2 at 850 oC for 10 min. Bubble .5-.8 SLM Ar through ethanol at 850 oC for 20 min.

• Ultralong single-wall carbon nanotubes, L. X. Zheng, 2004
  1. Recipe: FeCl3 catalyst, .0282 SLM Ar + .0018 SLM H2 at 900 oC for 30 min. Bubble .0192 SLM Ar + .0012 H2 through ethanol at 900 oC for 1 hr.

• Optimization of CCVD synthesis conditions for single-wall carbon nanotubes by statistical design of experiments (DoE), A´. Kukovecz, 2005
  1. Recipe: Fe:MgO catalyst, .372 SLM Ar + .01 SLM C2H2 at 863 oC for 20 min.

• Ultra-high-yield growth of vertical single-walled carbon nanotubes: Hidden roles of hydrogen and oxygen, G. Zhang, 2005
  1. Recipe: Fe catalyst, O2 at 550 oC for 10 min. H2 at 720 oC until warm. .053 SLM Ar +.03 SLM H2 + .16 SLM CH4 + .0024 SLM O2 at 720 oC for 30 min.

• Guided Growth of Large-Scale, Horizontally Aligned Arrays of Single-Walled Carbon Nanotubes and Their Use in Thin-Film Transistors, C. Kocabas, 2005
  1. Recipe: Ferritin catalyst, air at 900 oC for 10 min., then cooled. H2 at 900 oC for 1 min. 0.75 SLM H2 + 2.5 SLM CH4 at 900 oC for 10 min. Cooled <5 o per min. Quartz annealed at 900 oC for 10 min, 4 hr, 7hr.

• Two-Stage Growth of Single-Walled Carbon Nanotubes, H. Qi, 2007
  1. Recipe: Fe catalyst, 2 SLM H2 at 800 oC until warm. .794 SLM Ar + 1.2 SLM H2 + .006 SLM C2H6 at 800 oC for 1 min. 1.2 SLM H2 + .8 SLM CH4 at 800 oC for 9 min.

• High-performance electronics using dense, perfectly aligned arrays of single-walled carbon nanotubes, S Kang, 2007
  1. Recipe: Fe catalyst, air at 550 oC for 10 min. H2 at 900 oC for 5 min. 0.3 SLM H2 + 1.9 SLM CH4 at 900 oC for 1 hr. Quartz annealed at 900 oC for 8 hours.

L. Huang and G. Zhang speak on the physical role of ethanol. I'm interested to try combining the two-stage growth idea with the procedures for long tubes.

The importance of adding some H2 the gas flow is discussed in some papers from the Dai group, see Franklin et al. APL 79, 4571 (2001).