Silicon Technology - Facts and Perspectives

Transcription

1 Silicon Technology - Facts and Perspectives Photovoltaik-Symposium Neue Photovoltaiktechnologien Innovation durch Synergie 15. / 16. November 2007 Bitterfeld-Wolfen Prof. Dr. Norbert Auner

2 The Universe of Silicon Technology PUBLICATIONS INDUSTRY SALES Si 9 PATENTS PRODUCTS 52,000 (1995) 29, (1995) $6.6B (1995) 500 $4.3B $2.7B (1990) 50 > $75M

3 Silicon Based Technology R n SiCl 4-n, esp. R = Me, n = 2 SiO 2 Silicon SiCl 4, Si(OR) 4, HSi(OR) 3 HSiCl 3, SiH 4, (H 2 Si) n storage for hydrogen silicones sol-gel-processes; surface chemistry photovoltaic and electronic grade silicon silicon as secondary energy carrier

4 Conventional Silicon Production SiO C Si + 2 CO Reduction process: 84% energy efficiency (real) chemical energy input electrical energy input recoverable energy 3 kwh / kg Si 11 kwh / kg Si 2 kwh / kg Si net consumption 12 kwh / kg Si Si price / t Silicon 1217 USD (USA) 784 USD (Japan) Fe-Si (75) 585 USD (USA) 516 USD (China)

5 From Sand to Amorphous Silicon 59 kj + CaF 2 + H 2 SO 4 CaSO HF SiO HF SiF H 2 O SiF Na solvent gas phase r.t. 120 C 300 C 4 NaF + Si am Closed Cycle

6 Oxygen Content (Si/SiO 2 ) Determined by EDX (Si samples heated in air) At% O Wacker Si 0-70 µm Si am,mg Si am,ye Si am,bl Si am,bl,5d RT 84.8 % conversion 74.4 % conversion 51.6 % conversion Temperature [ C]

7 Photovoltaic Applications Yesterday and Today

8 Photovoltaic Applications Today and Tomorrow

9 Especially Japan and Germany have noticed significant growth rates.

10 with the consequence of an ongoing shortfall of Solar Silicon, the raw material for PV-wafers

11 Purification of Metallurgical Silicon

12 Process Flow for the Production of Polycrystalline Silicon Chlorination Plant H 2 Distillation Plant Reduction Plant Pure Silicon Finishing Plant CVD Reactor Silicon granules HCl Gas Fluidized Bed Reactor Crude TCS, STC Liquid STC TCS TCS Hydrogen Recycle Plant H 2 H 2 + TCS+STC Gas Lumps, Rods, Chunks Customer year 2005 [tons] TCS / STC Liquid

13 Reactions of Silicon with HCl Yield MW: HSiCl 3 = 97% % Chlorosilane thermal reaction Temperature [ C] HSiCl 3 SiCl 4

14 Semiconductor Production Steps

15 Reactions of Dismutation

16 Pyrolysis of SiH 4 in a Tube Reactor

17 Production Pathways to Polysilicon TCS-Synthesis Si + 3 HCl SiHCl 3 + H 2 Siemens type deposition 4 HSiCl 3 Si + 3 SiCl H 2 SiHCl 3 STC-Conversion Si + 3 SiCl H 2 4 SiHCl 3 Fluidized-bed deposition SiCl 4 ETHYL-Process SiF 4 + NaAlH 4 SiH 4 (too expensive) Redistribution 4 SiHCl 3 SiH SiCl 4 17 kg 1 kg 16 kg SiH 4 1 kg Si > 18 kg SiCl 4 Siemens type deposition SiH 4 Si + 2 H 2 expensive routes to mainly produce SiCl 4 Fluidized-bed deposition

18 Microwave Assisted Plasma Deposition of Silicon from the System SiCl 4 /H 2 Under reduced pressure Pressure: 2 kpa SiCl 4 /H 2 ratio: 1/2 Duration: 12 Power input: W SiCl 4 input: 1.74 mmol Small silicon sinter for ignition of plasma Temperature: no visible glowing Deposition takes place rapidly SiCl H 2 Si + 4 HCl Yield of Si: 64% = 31 mg Deposited Si is amorphous or crystalline depending on the temperature of the glass wall

19 Analysis of the Solid Product Element Spect. Typ Weight % Atom % O ED Cl ED Si ED

20 Microwave Assisted Plasma Deposition of Silicon from the System SiF 4 /H 2 Under reduced pressure Pressure: 2 kpa SiF 4 /H 2 ratio: 2/1-1/1 Duration: 15 Power input: W SiF 4 input: 12 mmol Small silicon sinter for ignition of plasma Temperature: no visible glowing, but plasma discharge Deposition takes place SiF H 2 Si + 4 HF Yield of Si: 7% = 24 mg

21 Analysis of Deposition Product Element Spect. Typ Weight % Atom % O ED F ED Si ED

22 Microwave Assisted Plasma Deposition of Silicon from the System SiCl 4 /H 2 at Low Power Input Under reduced pressure Pressure: Pa SiCl 4 /H 2 ratio: 1/10 (saturated at RT) Duration: 1 h Power input: 50 W Small electrical current (Townsend discharge or glowing discharge) applied to ensure ignition of mw-plasma Temperature: no glowing, only plasma discharge Yield: 2 g (not optimized) Deposited product: viscous oil or amorphous solid

23 Analysis of Deposited Solids: (Cl 2 Si) n Sample from the brown region Element Spect. Typ Weight % Atom % O ED Cl ED Si ED Sample from the white region Element Spect. Typ Weight % Atom % O ED Cl ED Si ED

24 City Solar Pilot Plant yearly production capacity [in tons] 10,0 1,0 0,1 0,01 ~50kg/a ~1,0t/a ~10t/a New Reactor- Typ 0,001 0,0001 0, ,01kg/a Q2/2005 1kg/a under construction Q4/2005 Q1/2006 Q4/2006 Q3/ SiO 2 4 HCl 2 CO + 2 H 2 2 CO 2 H 2 (Cl 2 Si) n SiCl 4 2 H 2 -SiCl 4 Si 4 HCl

25 Carbon Free Silicon Production SiO 2 4 HF O 2 2 H 2 O 2 H 2 (F 2 Si) n SiF 4 Laboratory scale device for microwave assisted polysilane and silicon production -SiF 4 Si 2 H 2 4 HF T Perfluorinated polysilane, (F 2 Si) n REM picture of silicon from the carbon free fluorine route

26 5000 t MG-Si Combination of Processes? chlorination, condensation, distillation Si + 3HCl SiHCl 3 +H t HSiCl t H 2 deposition 4 HSiCl 3 Si + 3SiCl 4 +2H t 1000 t Si 1600 t H 2 condensation t 100 t H pyrogenic silicic t HSiCl 3 acid (silica) distillation AEROSIL t SiCl 4

27 Combination of Processes is a Simple Option! t HSiCl t H 2 deposition 4 HSiCl 3 Si + 3SiCl 4 +2H t Si + ~3600 t Si ~4600 t Si t t SiCl 4 condensation thermolysis 1600 t H 2 2Si n Cl 2n Si + SiCl t t Si n Cl 2n t H t HSiCl 3 distillation plasma polymerisation SiCl 4 + H 2 Si n Cl 2n + 2 HCl 100 t H t SiCl t HCl t H 2

28 Facts and Perspectives HCl SiCl 4 SiCl 4 Plasma- Process perchlorinated polysilanes Si n Cl 2n ; Si n Cl 2n+2 Pyrolysis 350 C PV-Silicon HPS solid H-Polysilanes (HPS)

29 CO 2 -Free Alternative Fuel Si 4 H n Si 5 H n Si 6 H n Si 7 H n Si 8 H n Si 9 H n Si 10 H n Si 11 H n Si 12 H n Si 13 H n Octasilane Octane Si 14 H n Si 15 H n Si 16 H n Si 18 H n

30 HPS Surpasses DOE Targets Significantly H-SILANE ÜBERTREFFEN DOE TARGETS SIGNIFIKANT 25% 20% 20,35% 15% percent 10% 5% 6,50% 4,50% 0% US-DOE-target State of the art HPS (20% H2) R1 DOE Targets: weight of tank max. 46 kg/100 kwh volume of tank max 48 l/100 kwh hydrogen storage capacity min 6,5 wt. %

31 Energy Output per 1 kg of Energy Carrier in Driving Engines Energieumsatz im Antriebsmotor pro eingesetzter Menge des Energieträgers Diesel Combustion in an Diesel Engine 4,21 energy carrier Benzin HPS (20% H2) Combustion in an Otto Engine Combustion: 2,21 H 2 HPS 3,52 3,86 HPS (20% H2) Hydrogen in a PEM Fuel Cell 3,36 0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 kwh/kg

32 Volume Required for Storage of 10 kg Hydrogen Volumenbedarf von 10 kg gespeichertem Wasserstoff CH2 (350 bar) Compressed hydrogen, 350 bar 417 Wasserst Hydroge en toffquelle source CH2 (700 bar) LH2 Compressed hydrogen, 700 bar 143 Liquid hydrogen 200? System volume: material + empty space + insulation 249 HPS (20% H2) compact 50 71,4 System volume: material + empty space sphere packing + 4% functional layer on spheres Volumen [L]

33 The Concept

34 HYFORUM 2000: The energy carrier of the new century is hydrogen problem: low efficiency Electricity H 2 Renewable Energy problems: loss by transportation no long time storage immediate use required Water Electrolysis problems: transportation storage cost intensive infrastructure environment - availability, but no need - need, but no availability problem: lack of H 2 O Statement of the Energy Departement, Washington DC, July 2002: we are looking for revolutionary new energy production schemes, being convinced that incremental progress and all of the conventional approaches to fuel cells, photovoltaics, fossil fuels etc., aren t going to be sufficient for the future. Simply, our need is a secondary energy carrier, which is transportable without hazards. Statement of J. Hambrecht, Chief Executive of BASF, The Economist, Nov. 4th, 2006: Our fantasy is that in the future solar energy will be stored and put to work chemically, much as it is in plants through photosynthesis. Today s need: - > 50Mio t/year - > 90% petrochemistry - < 7.5% H 2 O electrolysis Excess of Renewable Energy Need of Energy

35 Proposed Long Term Solution E E C CO 2 Si SiO 2 photosynthesis Abundance C: 0,02 % Organo-C: % (!) solar energy 26,3 % Si 56,4 % SiO 2 C n H 2n+2 Si n H 2n+2 C Si* Energy content [kj/g)** 32,8 32,6 Energy density [kj/ml)** 74,2 75,9 ** obtained from heat of formation of the oxides

36 Water- Electrolysis trzr Silicon Transport and Storage H 2 O T / [H] H 2 O H SiX 4 (X 2 Si) n [H] (X = Cl, F) (H 2 Si) n H 2 O H 2 SiO 2 Electricity and Water PEM Fuel Cell

37 Acknowledgements Wacker Chemie GmbH Dow Corning Corporation City Solar AG Dr. Rumen Deltschew Dr. Gerd Lippold Dr. Sven Holl Dr. Christian Bauch Cooperations Prof. Dr. G. Tsatsaronis (Berlin) Prof. Dr. B. Kolbesen (Frankfurt / Main) Prof. Dr. M. Holthausen (Frankfurt / Main) Prof. Dr. M. Wagner (Frankfurt / Main) AK Prof. Norbert Auner Coworkers Martin Bleuel Dr. Jens Elsner Dr. Alireza Haghiri Andreas Hess Dr. Javad Mohsseni Ala Simon Nordschild Natalie Spomer Dr. Fariba Maysamy Tmar Dr. Yu Yang