(1) A sheet of graphene that is only one atom thick. Graphene nanosheets are used in batteries and supercapacitors to provide faster charging and long life. See
graphene.
(2) A 2D sheet of silicon from one to 100 nanometers thick. Nanosheets are used to form transistors as they reach below five nanometers. They are an improvement over FinFET transistors because they enable the gate to wrap around all four sides of the lines that go from source to drain instead of only three sides. See
GAAFET.