• Researchers at Delhi’s National Physical Laboratory (CSIR-NPL) have designed a low-pressure chemical vapour deposition (LPCVD) device that allows high quality, single-layer graphene measuring 4 inches in length and 2 inches in width to be grown.
  • The quality of the single-layer graphene is metrology-grade, and can be used in next-generation quantum devices.
  • The thickness of a single layer is 0.34 nanometre and average grain size of graphene is 1-3 micrometre.
  • Though there are about one billion grains in 4×2 square-inch single-layer graphene, the grains are highly connected to give a single continuous layer of graphene.

Tell us about the Cost-effectiveness

  • The LPCVD device developed indigenously costs about Rs.5,00,000, which is one-tenth of the imported ones.
  • More importantly, the quality of the single-layer graphene grown using this device is superior than the ones reported in the literature.
  • By growing single-layer graphene of high quality repeatedly for up to 30 times, the team has demonstrated reproducibility.
  • It is possible to grow single-layer graphene measuring 6×4 square-inches but the quality will not be as good as when we grow graphene of smaller dimensions.
  • This is because when attempts are made to grow larger graphene single layers, it is difficult to control the diffusion of carbon atoms which get deposited on the copper substrate.
  • This compromises the quality of graphene single layer produced.
  • Generally, LPCVD devices have three mass flow meters through which hydrogen, argon and hydrocarbon gases are supplied to grow the graphene.
  • Since the mass flow meters are expensive the team replaced two such meters that supply argon and hydrocarbon with calibrated rotameters.
  • Unlike hydrogen, both argon and hydrocarbon have higher molecular weight and so it is easy to control the flow these gases.
  • The graphene was grown on a substrate made of copper, which acts as a catalyst.