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![Page 1: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/1.jpg)
Silicon Nanowire based Solar Cells
International Congress On Renewable EnergyICORE 2010
2nd December, 2010.Pragya Singh
Pratul K Singh
![Page 2: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/2.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 3: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/3.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 4: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/4.jpg)
Light Trapping in Cells:
ICORE - 2010, Pragya Singh, Pratul K Singh
Sun already provides all the energy needed to support life.
So the Challenge?
![Page 5: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/5.jpg)
Light Trapping in Cells:
ICORE - 2010, Pragya Singh, Pratul K Singh
One to One conversion:Blue photon = 2 times more energy than the Red Photon Both produce 1 electron each.
Effective light energy utilized?
![Page 6: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/6.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 7: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/7.jpg)
Solar Cell• Cell is thin Si wafer
• Size 10x10 cm : size of a CD
• Thickness is in fractions of mm
• Metal pattern is to make electrical contacts.
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 8: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/8.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 9: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/9.jpg)
Energy Conversion in Solar Cell
Light is shone Electrons are knocked out Electrons and holes move in opposite directions Electrical output is generated between the contacts.
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 10: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/10.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 11: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/11.jpg)
Solar Cells Everywhere
Solar cells :SafeCleanQuietDurableReliableInstallable anywhere
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 12: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/12.jpg)
The Main Catch
ICORE - 2010, Pragya Singh, Pratul K Singh
Material Cost
Thickness of material Purity
Fabrication Cost
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Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 14: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/14.jpg)
Planar Silicon Solar Cells:
ICORE - 2010, Pragya Singh, Pratul K Singh
Thickness for an efficient light absorption
High purity to avoid recombining
High Reflectance
High Recombination Rate.
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Sliced into Nano-scale
ICORE - 2010, Pragya Singh, Pratul K Singh
Diameters from 1 to 50nm
Nano scale Silicon has a color difference
Quantum Confinement Nano sized Silicon shows:
Physical Optical Electronics properties change Electrons occupy different energy levels
![Page 16: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/16.jpg)
Conductance can be Improved
ICORE - 2010, Pragya Singh, Pratul K Singh
Bulk Silicon atom:TetravalentTend to achieve StabilityBond with 4 other atoms
Silicon Nanowire:TetravalentTend to achieve stabilityCling with atmospheric OxygenSilica is formed
![Page 17: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/17.jpg)
ICORE - 2010, Pragya Singh, Pratul K Singh
Prevention of Silica:
Conductivity increases 10 timesPrevention at high temperatures – 700CHigh Vaccum
Conductance can be Improved
![Page 18: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/18.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 19: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/19.jpg)
– No Lattice Mismatch.
– Flexibility to create heterostructures.
– Broad range of materials.
– Integration of compound semiconductor based optoelectronic devices with silicon based microelectronics.
ICORE - 2010, Pragya Singh, Pratul K Singh
Nanowires- Properties
![Page 20: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/20.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 21: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/21.jpg)
Recombination:
• Poor efficiency may be due to recombination within the bulk silicon element.
• Photon strikes the p-n junction in bulk silicon, Produces an electron-hole pair.
• Electron and hole must travel along the wire to produce current.
ICORE - 2010, Pragya Singh, Pratul K Singh
Silicon Nanowires- Properties
![Page 22: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/22.jpg)
Recombination:
Tendency to recombine with other oppositely charged charge carrier
Resulting in heat generation rather than electrical energy
ICORE - 2010, Pragya Singh, Pratul K Singh
Silicon Nanowires- Properties
![Page 23: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/23.jpg)
Reduced Recombination in SiNW:Small diameters. SiNWs grown vertical, perpendicular to the surface of the substrate.Electrons strikes on the surface.Distance of hole/electron travel is minimized. Distance is of the order of nanometers.
ICORE - 2010, Pragya Singh, Pratul K Singh
Silicon Nanowires- Properties
![Page 24: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/24.jpg)
Light Trapping:
Light falling on the substrate gets reflected and once again gets absorbed by silicon nanowires.
ICORE - 2010, Pragya Singh, Pratul K Singh
Silicon Nanowires- Properties
![Page 25: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/25.jpg)
Increased Surface Area:Very narrow pointed structures. Diameter in nanometers.Length in micrometers. Greater area made of p-n junctions is exposed to sunlight.Increases absorptivity.
ICORE - 2010, Pragya Singh, Pratul K Singh
Silicon Nanowires- Properties
![Page 26: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/26.jpg)
ICORE - 2010, Pragya Singh, Pratul K Singh
Reduced size
Increased absorptivity
Reduced reflectivity
Efficient electron transport
Reduced Recombination
Silicon Nanowires- Properties
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Silicon Nanowires- Properties
Tiny PV Cells:
Composed of 3 layers: – Inner P region
– Intrinsic or pure silicon
– Outer N region
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 28: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/28.jpg)
Silicon Nanowires- Properties
Photon strikes the outer shellElectron-hole pair is created Travels in the radial direction towards the P layer
(core) before recombination.
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 29: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/29.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 30: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/30.jpg)
Fabrication
• Catalyst Particles :
• The catalyst must be inert to the reaction products (during CVD nanowire growth).
• Gold
• Aluminum
• Tin
• Indium
• Gallium
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 31: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/31.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 32: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/32.jpg)
Techniques for SiNW DepositionTechniques:
Supercritical-Fluid-Based and Solution-Based Growth Techniques
Molecular Beam EpitaxyLaser AblationSilicon Monoxide EvaporationPECVD
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 33: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/33.jpg)
Silicon Nanowire based Solar Cells
ICORE - 2010, Pragya Singh, Pratul K Singh
Outline:
•Light Trapping in Cells•Solar Cell•Energy Conversion in Solar Cell•Solar Cells Everywhere•Planar Silicon Solar Cell•Nanowires- Properties•Silicon Nanowires- Properties•Fabrication•Techniques for SiNW Deposition•Experiment at the SSN Research Centre
![Page 34: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/34.jpg)
Experiment at the SSN Research Centre
ICORE - 2010, Pragya Singh, Pratul K Singh
![Page 35: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/35.jpg)
Si-NW Growth Principle
ICORE - 2010, Pragya Singh, Pratul K Singh
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Si-NW Deposition Process Steps
ICORE - 2010, Pragya Singh, Pratul K Singh
• Silicon (4 inch) n-type Substrate Cleaned
• Chromium layer of 10.7nm deposited by EBE Method
• Gold Layer of 2.6nm deposited by EBE Method
• The sample introduced in the PECVD chamber
• Heated to 580 degrees to form Nano particles
• Silane introduced with hydrogen for 30 minutes at various temperatures
![Page 37: Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.](https://reader036.fdocuments.in/reader036/viewer/2022081504/56649cd95503460f949a2c5c/html5/thumbnails/37.jpg)
SiNW – Deposition Experiment• Catalyst Nano Particles:
– Gold Film Layer (2.6nm) Deposited on Silicon Substrate by EBE
– Heated at 580 degrees to form Nano Particles
– Figure1 SEM image of Nano particles of Gold
Figure 1. SEM Image of Gold Nano Particles on Silicon Substrate
ICORE - 2010, Pragya Singh, Pratul K Singh
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SiNW – Deposition ExperimentPECVD system.
Temperature : 380 degrees
Pressure in mTorr : 500mT
Time of Deposition : 30 minutes
Gases Used : Silane, Hydrogen and Argon
ICORE - 2010, Pragya Singh, Pratul K Singh
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Si NW Comparison
Si Nano Wire at SSNRC Literature Survey Reference: IRAM, Saclay Institute of Matter and Radiation
ICORE - 2010, Pragya Singh, Pratul K Singh
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Thank You
ICORE - 2010, Pragya Singh, Pratul K Singh