  We present low-frequency electrical resistance fluctuations, or noise, in
graphene-based field-effect devices with varying number of layers. In
single-layer devices the noise magnitude decreases with increasing carrier
density, which behaved oppositely in the devices with two or larger number of
layers accompanied by a suppression in noise magnitude by more than two orders
in the latter case. This behavior can be explained from the influence of
external electric field on graphene band structure, and provides a simple
transport-based route to isolate single-layer graphene devices from those with
multiple layers.
