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Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh.

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Presentation on theme: "Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE 2010 2 nd December, 2010. Pragya Singh Pratul K Singh."— Presentation transcript:

1 Silicon Nanowire based Solar Cells International Congress On Renewable Energy ICORE nd December, Pragya Singh Pratul K Singh

2 Silicon Nanowire based Solar Cells ICORE , 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

3 Silicon Nanowire based Solar Cells ICORE , 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

4 Light Trapping in Cells: ICORE , Pragya Singh, Pratul K Singh Sun already provides all the energy needed to support life. So the Challenge?

5 Light Trapping in Cells: ICORE , 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?

6 Silicon Nanowire based Solar Cells ICORE , 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

7 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 , Pragya Singh, Pratul K Singh

8 Silicon Nanowire based Solar Cells ICORE , 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

9 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 , Pragya Singh, Pratul K Singh

10 Silicon Nanowire based Solar Cells ICORE , 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

11 Solar Cells Everywhere Solar cells : Safe Clean Quiet Durable Reliable Installable anywhere ICORE , Pragya Singh, Pratul K Singh

12 The Main Catch ICORE , Pragya Singh, Pratul K Singh  Material Cost  Thickness of material  Purity  Fabrication Cost

13 Silicon Nanowire based Solar Cells ICORE , 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

14 Planar Silicon Solar Cells: ICORE , Pragya Singh, Pratul K Singh  Thickness for an efficient light absorption  High purity to avoid recombining  High Reflectance  High Recombination Rate.

15 Sliced into Nano-scale ICORE , 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

16 Conductance can be Improved ICORE , Pragya Singh, Pratul K Singh Bulk Silicon atom: Tetravalent Tend to achieve Stability Bond with 4 other atoms Silicon Nanowire: Tetravalent Tend to achieve stability Cling with atmospheric Oxygen Silica is formed

17 ICORE , Pragya Singh, Pratul K Singh Prevention of Silica: Conductivity increases 10 times Prevention at high temperatures – 700C High Vaccum Conductance can be Improved

18 Silicon Nanowire based Solar Cells ICORE , 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

19 – No Lattice Mismatch. – Flexibility to create heterostructures. – Broad range of materials. – Integration of compound semiconductor based optoelectronic devices with silicon based microelectronics. ICORE , Pragya Singh, Pratul K Singh Nanowires- Properties

20 Silicon Nanowire based Solar Cells ICORE , 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

21 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 , Pragya Singh, Pratul K Singh Silicon Nanowires- Properties

22 Recombination: Tendency to recombine with other oppositely charged charge carrier Resulting in heat generation rather than electrical energy ICORE , Pragya Singh, Pratul K Singh Silicon Nanowires- Properties

23 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 , Pragya Singh, Pratul K Singh Silicon Nanowires- Properties

24 Light Trapping: Light falling on the substrate gets reflected and once again gets absorbed by silicon nanowires. ICORE , Pragya Singh, Pratul K Singh Silicon Nanowires- Properties

25 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 , Pragya Singh, Pratul K Singh Silicon Nanowires- Properties

26 ICORE , Pragya Singh, Pratul K Singh Reduced size Increased absorptivity Reduced reflectivity Efficient electron transport Reduced Recombination Silicon Nanowires- Properties

27 Tiny PV Cells: Composed of 3 layers: – Inner P region – Intrinsic or pure silicon – Outer N region ICORE , Pragya Singh, Pratul K Singh

28 Silicon Nanowires- Properties Photon strikes the outer shell Electron-hole pair is created Travels in the radial direction towards the P layer (core) before recombination. ICORE , Pragya Singh, Pratul K Singh

29 Silicon Nanowire based Solar Cells ICORE , 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

30 Fabrication Catalyst Particles : The catalyst must be inert to the reaction products (during CVD nanowire growth). Gold Aluminum Tin Indium Gallium ICORE , Pragya Singh, Pratul K Singh

31 Silicon Nanowire based Solar Cells ICORE , 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

32 Techniques for SiNW Deposition Techniques: Supercritical-Fluid-Based and Solution-Based Growth Techniques Molecular Beam Epitaxy Laser Ablation Silicon Monoxide Evaporation PECVD ICORE , Pragya Singh, Pratul K Singh

33 Silicon Nanowire based Solar Cells ICORE , 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

34 ICORE , Pragya Singh, Pratul K Singh

35 Si-NW Growth Principle ICORE , Pragya Singh, Pratul K Singh

36 Si-NW Deposition Process Steps ICORE , 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

37 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 , Pragya Singh, Pratul K Singh

38 SiNW – Deposition Experiment PECVD system. Temperature : 380 degrees Pressure in mTorr : 500mT Time of Deposition : 30 minutes Gases Used : Silane, Hydrogen and Argon ICORE , Pragya Singh, Pratul K Singh

39 Si NW Comparison Si Nano Wire at SSNRC Literature Survey Reference: IRAM, Saclay Institute of Matter and Radiation ICORE , Pragya Singh, Pratul K Singh

40 Thank You ICORE , Pragya Singh, Pratul K Singh


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