Chemistry Reference
In-Depth Information
Fig. 5. (a) Optical micrograph of the dual gated BLG device used in the experiment.
The scale bar is 10
µ
m.(b) Resistance versus topgate voltage for various back gate volt-
ages, ranging from 30 V to
−
30 V (left to right) with an interval of 5 V. Insets show
schematics of corresponding band structures. (c-e) Electrical transport and noise char-
acterization of a BLG device. The resistance and the normalized noise power spectral
density (
N
R
) as functions of top gate voltages are shown for various back gate voltages:
(c) 30 V, (d) 0 V, and (e) -30 V. The thick solid lines are guide to the eye. The in-
sets show typical normalized noise power spectra
S
R
/R
2
, far from the charge neutrality
point for each back gate voltage. Note that the charge neutrality points and the noise
minimum points are not necessarily the same. This can be explained quantitatively
by considering the noise minimum point in graphene to correspond to zero band gap
between the conduction and the valence bands.
Typical power spectra of resistance noise are shown in the insets of
Figs. 5(c)-(e). Figures 5(c)-(e) show the variation of
N
R
and the corre-
sponding average resistance as functions of
V
tg
at three different values of
V
bg
. For all
V
bg
,
N
R
shows a minimum at a specific
V
tg
, denoted as
V
Nmin
tg
,
and increases monotonically on both sides of
V
Nmin
tg
. Similar behavior
was observed for noise in BLG nanoribbons as well,
44
which confirms this
to be an intrinsic characteristic of BLG, although
V
Rmax
tg
Nmin
tg
and
V
are
