▎ 摘　　要

NOVELTY - The FET (20) has an electrically conducting and chemically sensitive channel (2) extending between a drain electrode (6) and a source electrode (5). A gate electrode (7) is arranged at distance from the channel such that the gate electrode and the channel are separated by a gap (10). The channel comprises a continuous monocrystalline graphene layer (2a) arranged on an electrically insulating graphene layer substrate (1), where the graphene layer extends between the source and the drain electrodes. USE - FET for use in a chemical sensor for sensing chemical from ambient environment e.g. gaseous ambient environment such as air environment, and liquid ambient environment (all claimed). ADVANTAGE - The graphene layer is arranged on the graphene layer substrate, thus increasing reproducibility and reducing risk of damage to the graphene layer during production of the FET and enabling low detection limits with low variability between transistors. DETAILED DESCRIPTION - The graphene layer is an epitaxial layer. The graphene layer substrate is a silicon carbide substrate. INDEPENDENT CLAIMS are also included for the following: (1) a chemical sensor (2) a method for producing a FET. DESCRIPTION OF DRAWING(S) - The drawing shows a side view of a FET for use in a chemical sensor. Electrically insulating graphene layer substrate (1) Electrically conducting and chemically sensitive channel (2) Continuous monocrystalline graphene layer (2a) Source electrode (5) Drain electrode (6) Gate electrode (7) Gap (10) FET (20)