Graphene
Transparent On-line AFM & Raman Integration Without Top or Bottom AFM Optical Interference
Investigation of Graphene on Silicon
Online AFM/Raman Imaging(a)Optical top-view of Graphene
flake on Silicon performed with
100x objective (NA=0.75) of an
upright microscope during
AFM/Raman imaging.

(b)

10x10 µm AFM Height
image of single and double
layer of Graphene.

(c)

(d)

Height line profile at thegreen line shown in (b) ofthe Graphene single layer.

AFM 3D Image of Graphene.

(e)(e) Graphene Raman spectra of Single Layer (Red), Double Layer(blue and black) at the marked area on (a). The red spectrum
corresponds to the single layer graphene shown in (b). Blue andblack corresponds to double & multii layers on the red area of map-1(c). The 2700cm peak alteration in this area are due to alterations
in numbers of layers of graphene.

(f)

(g)

DL(h(i)

SLDL

Raman Intensity map of-1
the 2676 cm 2D single
layer band. The map wasobtained during online
AFM Raman image withfull correlation to the AFM
image presented on (b)AFM/Raman Collage image
1
showing the 2676 cmband's intensity mergedwith the AFM topography.
The colors represent theRaman intensities wherered is the highest.

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Raman Intensity map of-1
the 2700 cm double layer
band. The map wasrecorded during online
AFM Raman scan with fullcorrelation to the AFM
image presented on (b)AFM/Raman Collage image
1
showing the 2676 cmband's intensity mergedwith the AFM topography.
The colors represent theRaman intensities where
red is the highest.

The Next Evolution in SPM

Graphene

The Next E volut ion in SP M

www.nanonics.co.il

Transparent AFM & Raman Integration Without Top or Bottom AFM Optical Interference
Investigation of Graphene on Silicon

Graphene Online AFM/Raman Imaging
(a)

(b)

(c)

SL

(d)

DLML
Si

Optical top-view picture ofGraphene flake on Silicon
performed with an uprightmicroscope 100x objective(NA=0.75) during AFM/Raman
imaging.

AFM topographic image ofGraphene performed at themarked square in (a) showing
single, double and multilayers of Graphene.

Zoom of the AFM image (b) of the single layer area marked
by a yellow square in (b). The presence of a Single GrapheneLayer is clearly seen through the height line profile (d) andthe subsequent Raman maps.

(e)Selected Graphene Raman spectra of Single Layer (Red), DoubleLayer (Green) and Multi Layer (Blue) at the marked areas on theAFM image (b above) acquired during AFM/Raman imaging.
Corresponding Raman maps for intensities of the single layer (f),double layer (g) multi layer (h) bands are presented below. The mapin (i) shows the Intensity of and the 1582 cm-1 G band where thesingle layer contribution is minimum compared to the double andmulti layers. Red refers to higher intensities and blue to lowest (6 x6µm area)

(f)

(g)

(h)

Graphene Tip Enhanced Raman Spectroscopy (TERS)Left:Gold nanoparticle probe
illustration for Tip Enhanced Raman
Spectroscopy with high dielectric
contrast & well-defined plasmon
resonance provides clear optical axis
from below and above.
Middle: On-line optical microscope
top view of TERS Probe in contact
with single layer Graphene.
Right: Raman spectrum of Graphene(black)andenhanced
Raman
spectrum (red) correlated with theoptical microscope images (middle).

(i)TERS of Graphene On Insulating Silicon Oxide
Unique High Dielectric Contrast Optically Friendly& Raman Background Free NanoParticle Probes
Tip Enhanced Raman Spectroscopy (TERS) of a Graphene Flake on Insulator Critical Issues:• TERS Probe: Unique high dielectric contrast gold nanoparticle probe with defined plasmon resonance• Independent Tip and Sample Scanning AFM Head: Tip piezo scanning allows for maximizing Z polarization excitation even when using
conventional Raman excitation with a Gaussian focused laser beam. In addition, Tip scanning is required for Difference RamanProtocols where the TERS signal is evaluated as a difference between the Near-field signal (when the tip is in feedback with thesurface) and the far-field signal (when the tip is retracted). Sample scanning on the other hand is required not only for Raman dataacquisition but also for feedback to keep the sample-lens distance identical for each pixel in the Raman image with on-line AFM
autofocus the best method for insuring true chemical contrast without sample topography or less than parallel sample placement• Free Optical Axis AFM/Raman TERS: For maximizing signal with high numerical aperture conventional top down illumination criticalfor opaque grapheme on silicon samples

(b)

(a)

TERS measurement performed at the single
layer area indicated as (a) in the middle AFM
image. Black is the far-field Raman spectrum.
Red the enhanced spectrum when the TERS tip
is in contact. Green is the difference of these
two spectra. Note the width of the difference
signal. The single layer is principally responsible
for the enhancement even though the laser
excites this point & the surroundings

(c)

(b)

(a) (c) (d)AFM Height image ofGraphene flake.

TERS measurement performed at the double
layer area indicated as (b) on the middle AFM
image. Black is the far-field Raman spectrum.
Red is the enhanced spectrum when the TERS
tip is in contact. Green is the calculateddifference of these two spectra. Note that theprincipal enhancement is from the top layerin spite of the presence & the illumination ofthe bottom layer.

(d)

TERSmeasurements
were performed ateachofthealphabetically indicatedpoints.
The results are shownand described for eachof the spectra.
TERS measurement performed in the three(or four) layer area indicated as (c) in the AFM
image (middle). Black is the far-field Raman
spectrum. Red the enhanced spectrum when
the TERS tip is in contact. Green is thedifference of these two spectra. Note that theprincipal enhancement is from the top layer(left peak) in spite of the presence & theillumination of the bottom layers.

TERS measurement performed at the multiple
layers area indicated as (d) in the AFM image(middle). Black is the far-field Raman
spectrum. Red the enhanced spectrum when
the TERS tip is in contact. Green is thedifference of these two spectra.

The Next Evolution in SPM
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