Method of producing a two-dimensional material

A method of producing a two-dimensional crystalline material, the method comprising:

• providing a substrate having nucleation sites within a reaction chamber;
• introducing at a precursor entry point a precursor into the reaction chamber, the precursor being in a gas phase and/or suspended in a gas;
• heating the substrate to a temperature that is within a decomposition range of the precursor, and that allows two-dimensional crystalline material formation from a species released from the decomposed precursor;
• and
• cooling the precursor entry point;
• wherein the reaction chamber is a close coupled reaction chamber such that a separation between the substrate surface upon which the two-dimensional crystalline material is formed and the point at which the precursor enters the reaction chamber is sufficiently small, and a thermal gradient between the substrate surface and the point at which the precursor enters the chamber is sufficiently steep, such that the fraction of precursor that reacts in the gas phase within the reaction chamber is low enough to allow the formation of the two-dimensional crystalline material, wherein the distance between the surface of the substrate upon which the two-dimensional crystalline material is produced and the point at which precursor enters the chamber is less than 10 mm;
• and
• wherein the two-dimensional crystalline material is graphene and the species is carbon or wherein the two-dimensional crystalline material is silicene and the species is silicon;
• and
• wherein the substrate provides a non-metallic surface upon which the two-dimensional crystalline material is produced.