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| Method | Arc discharge | Laser ablation | Chemical vapour deposition |
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| Process | Connect two graphite rods to a power supply, place them a few millimetres apart. At 100 amps, carbon vaporizes and forms hot plasma.
| Blast graphite with intense laser pulses; use the laser pulses rather than electricity to generate carbon gas from which the CNTs form; try various conditions until hit on one that produces prodigious amounts of SWNTs. | Place substrate in oven, heat to high temperature, and slowly add a carbon-bearing gas such as methane. As gas decomposes it frees up carbon atoms, which recombine in the form of NTs. |
| Condition | Low-pressure inert gas (Helium). | Argon or Nitrogen gas at 500 Torr. | High temperatures within 500 to 1000°C at atmospheric pressure. |
| Typical yield | 30–90% | Up to 70% | 20–100% |
| SWCNT | Short tubes with diameters of 0.6–1.4 nm. | Long bundles of tubes (5–20 microns), with individual diameter from 1-2 nm. | Long tubes with diameters ranging from 0.6 to 4 nm. |
| MWCNT | Short tubes with inner diameter of 1–3 nm and outer diameter of
approximately 10 nm | Not very much interest in this technique, as it is too expensive, but MWNT synthesis is possible.
| Long tubes with diameter ranging from 10 to 240 nm |
| Carbon source | Pure graphite | Graphite | Fossil-based hydrocarbon and botanical hydrocarbon. |
| Cost | High | High | Low |
| Advantage | Can easily produce SWNT, MWNTs. SWNTs have few
structural defects; MWNTs without catalyst, not too
expensive, open air synthesis possible. | Good quality, higher yield, and narrower distribution of SWNT than arc-discharge. | Easiest to scale up to industrial production; long length, simple process, SWNT diameter controllable, and quite pure. |
| Disadvantage | Tubes tend to be short with random sizes and directions; often needs a lot of purification. | Costly technique, because it requires expensive lasers and high-power requirement, but is improving. | Often riddled with defects. |
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