University of Ioannina Department of Materials Science & Engineering Computational Materials Science
Elefterios Lidorikis Materials Science & Engineering, University of Ioannina, Greece
Plasmonic Near-Field Enhanced Absorption and Scattering
Crete, 8-11 June 2011
June 8-11, 2011 Crete, Greece
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Localized surface plasmon resonance
• Inside an electric field a nanoparticle gets polarized
• Surface plasmon resonance
• Strong scattering • Strong absorption • Strongly enhanced near fields
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Outline
• We will use a point-dipole approximation and consider two applications: – Enhanced solar cell absorption – Enhanced Raman scattering
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Enhanced solar absorption
• Metallic nanoparticles and/or nanostructures can be used: – on the surface – inside the semiconductor – on the back contact
• Enhancement due to: – scattering – LSPR near-fields
back metal contact
metal nanoparticles
back metal contact
metal nanodisks or nanowires
back metal contact
metal nanodisks or nanowires
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Theory of SPR near-field enhancement
x y
z
h
k,ω E0
2a Au nanoparticle
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Theory of SPR near-field enhancement
x y
z
k,ω E0
for a<<λ
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Theory of SPR near-field enhancement
φ
θ
x y
z
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Theory of SPR near-field enhancement
for r<<λ the dominant term is the
φ
θ
x y
z
absorption enhancement
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Absorption enhancement • at a point
• on a plane
• within a volume
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Planar absorption enhancement
– Multiple scattering → Claussius-Mossotti
– Absorption in the nanoparticle → reduced field strength
L
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Planar absorption enhancement
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Planar and volume absorption enhancement
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Volume enhancement of composites
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g Surface-Enhanced Raman Scattering
Schedin et al., ACS Nano 4, 5617 (2010)
virtual energy level
vibrational state ground state
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Theory of SERS in 2d
φ
θ
x y
z
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Theory of SERS in 2d
φ
θ
x y
z
This excites a Raman dipole
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Theory of SERS in 2d
φ
θ
x y
z
This excites a Raman dipole
which re-radiates exciting a secondary dipole in the nanoparticle
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Theory of SERS in 2d
φ
θ
x y
z
This excites a Raman dipole
which re-radiates exciting a secondary dipole in the nanoparticle
ks,ωs
total particle-induced Raman emission
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Theory of SERS in 2d
Normalize with the signal I0 expected without nanoparticles
L
assume square array with side L
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Validation of 2d SERS theory
Ex
Ey
10nm nanoparticles 140nm nanoparticles
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g FDTD SERS calculations: model
Au Cr SLG
Drude-Lorentz model: 1 free electron & N bound electrons
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g FDTD SERS calculations: method
monitor the field at graphene
Fourier transform
normalize to field without Au disks
absorption enhancement
emission enhancement
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Raman enhancement absorption enhancement
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g
Conclusions and acknowledgements
• Simple description of plasmonic near-field effects based on a discrete dipole – enhanced absorption in
semiconductors – SERS in 2d materials
• insight for designing plasmonic response
Happy Birthday Costa!
Computing time provided by RCSS Ioannina
Semiconductor absorption • University of Patras
– M.M Sigalas
• N.C.S.R “Demokritos” – N. Lagos
SERS in graphene • Cambridge University
– A.C. Ferrari – A. Lombardo
• University of Manchester – K.S. Novoselov – A.K. Geim – A.N. Grigorenko – F. Schedin – V.G. Kravets
Pla
smon
ic N
ear-
Fiel
d E
nhan
ced
Abs
orpt
ion
and
Sca
tterin
g FDTD scheme with dispersion
• Include polarization terms in Maxwell’s equations
reflection transmission
absorption effective medium
band structure