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Fiona BeckSmall Particles, Big Hopes:
Absorption Enhancement in Silicon using Metallic Nanoparticles
Centre for Super Earth-saving Science
Regular Superhero
Solar Energy Superheros
Absorption Spectra of Silicon
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Wavelength (nm)
%A
Rubbish absorption above 1000nm
Absorption Spectra of Silicon%
Abs
orpt
ion
Wavelength (nm)
Texturing to trap light in bulk silicon cells
light
SEM image of textured silicon taken by Luke Johnson
Localised Surface Plasmons in Metal Nanoparticles
-e -e-e -e -e
-e -e-e
+ + + + + +
- - - - - - -
-e -e-e-e
-e -e-e
-e
+ + + + + +
- - - - - - -
E-field
Incident Light
Time t Time t + /2c
Interface effects
Incident light
Induced surface plasmon
Light coupled into silicon in trapped modes
Silver Nanoparticle
Dielectric layer
1) Silicon wafer, thin and shiny
2) Dielectric film deposition ~30nm
Oxidation for SiO2
APCVD TiO2
Sample Fabrication:
3) Silver film evaporation ~10nm
4) Low temperature anneal ~260 degree C
Nanoparticles !
Resonance peaks
Bare Particle Resonances
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% E
xtin
ctio
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Ag 20.1 nmAg 18.2 nmAg 14.0 nmAg 9.7 nm
Smallest particles
Biggest particles
Bare Particle Resonances on TiO2-Glass
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Wavelength (nm)
%E
TiO2-1_Glass
TiO2-2_Glass
TiO2-3_Glass
TiO2-4_Glass
Optical measurements
Particles on front
Particles on rear
SiO2 Coating TiO2 Coating
Light source
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Wavelength (nm)
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Plain Si
Plain TiO2_Si
Ag particles SiO2_Si
Ag particles TiO2_Si
Absorption Spectra for Particles on Silicon
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Wavelength (nm)
%A
bsor
ptio
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Plain Si
Plain TiO2_Si
Ag particles SiO2_Si
Ag particles TiO2_Si
Absorption Spectra for Particles on Silicon
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Wavelength (nm)
%A
bsor
ptio
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Plain Si
Plain TiO2_Si
Ag particles SiO2_Si
Ag particles TiO2_Si
Absorption Spectra for Particles on Silicon
16 fold increase in light absorption for particles on TiO2 at 1150nm
5.6 times more absorption of light at 1150nm for particles on the rear of a silicon-SiO2 sample
Particles on TiO2 Particles on SiO2
SEM Images
My supervisors
Klaus Weber and Kylie Catchpole, currently at the Institute of Atomic and Molecular Physics in the Netherlands.
Luke Johnson for the TiO2 deposition and the nice SEM image and everyone who has helped me out in the labs.
