Silicon Technology- Facts and Perspectives
Photovoltaik-Symposium
“Neue Photovoltaiktechnologien –
Innovation durch Synergie“
15. / 16. November 2007Bitterfeld-Wolfen
Prof. Dr. Norbert Auner
The Universe of Silicon Technology
PUBLICATIONSINDUSTRY
SALES
PATENTSPRODUCTS
52,000(1995)
6000
29,000(1995) $6.6B
Si$2.7B
1
50
600
6000
9
19501930
6000500
(1995)
>5000
$6.6B(1995)
$4.3B(1990)
$75M
1970 20101990
Silicon Based Technology
SiO2 Silicon
RnSiCl4-n, esp. R = Me, n = 2
SiCl4, Si(OR)4, HSi(OR)3
HSiCl3, SiH4, (H2Si)n
storage for hydrogen
• silicones
• sol-gel-processes; surface chemistry
• photovoltaic and electronic grade silicon
• silicon as secondary energy carrier
SiO2 + 2 C � Si + 2 CO Reduction process:
84% energy efficiency (real)
chemical energy input 3 kWh / kg Si
electrical energy input 11 kWh / kg Si
recoverable energy 2 kWh / kg Si
Conventional Silicon Production
Si
price / t Silicon 1217 USD (USA)
784 USD (Japan)
Fe-Si (75) 585 USD (USA)
516 USD (China)
net consumption 12 kWh / kg Si
From Sand to
Amorphous Silicon
59 kJ + CaF2 + H2SO4 → CaSO4 + 2 HF
SiO2 + 4 HF → SiF4 + 2 H2O
solvent || gas phase
Closed Cycle
SiF4 + 4 Na 4 NaF + Siam
solvent || gas phase
r.t. →120°C|| 300°C
50
60
84.8 %
conversion
74.4 %
conversion
51.6 %
conversion
At% O
Oxygen Content (Si/SiO2) Determined by EDX
(Si samples heated in air)
0 200 400 600 800 1000 1200
0
10
20
30
40
conversion
Wacker Si 0-70 µm
Siam,Mg
Siam,ye
Siam,bl
Siam,bl,5d RT
Temperature [°C]
Photovoltaic – Applications Yesterday and Today
Photovoltaic – Applications Today and Tomorrow
Especially Japan and Germany have noticed
significant growth rates ….
… with the consequence of an ongoing shortfall
of Solar Silicon, the raw material for PV-wafers
Purification of Metallurgical Silicon
FluidizedBed
CVD
Reactor
Silicon
granules
ChlorinationPlant
CrudeTCS,
STC
DistillationPlant
Reduction
Plant
TCS
H2
PureSilicon
Lumps,Rods,
Chunks
Finishing
Plant
Process Flow for the Production of Polycrystalline Silicon
BedReactor
HCl Gas
STC
Liquid
H2TCSSTC
TCS / STC
Liquid
H2 + TCS+STCGas
Hydrogen Recycle Plant
Customer
year 2005
[tons]
Reactions of Silicon with HCl
Yield MW: HSiCl3 = 97%
80
90
100
thermal reaction
0
10
20
30
40
50
60
70
400 500 600 700 800 900 1000 1100
Temperature [°C]
% C
hlo
ros
ilan
e
SiCl4HSiCl3
Semiconductor Production Steps
Reactions of Dismutation
Pyrolysis of SiH4 in a Tube Reactor
Production Pathways to Polysilicon
TCS-Synthesis
Si + 3 HCl → SiHCl3 + H2
STC-Conversion
Si + 3 SiCl4 + 2 H2 → 4 SiHCl3
Siemens type deposition
Fluidized-beddeposition
SiHCl3
4 HSiCl3 →→→→ Si + 3 SiCl4 + 2 H2
ETHYL-Process
SiF4 + NaAlH4 → SiH4
Fluidized-beddeposition
Siemens typedeposition
SiH4 → Si + 2 H2
Redistribution
4 SiHCl3 → SiH4 + 3 SiCl4
SiH4
17 kg 1 kg 16 kg
1 kg Si →→→→ > 18 kg SiCl4
expensive routes to mainly produce SiCl4
(too expensive)
SiCl4
Pressure: ≅ 2 kPa
SiCl4/H2 ratio: ≅ 1/2
Duration: 12´
Power input: 200 – 320 W
Under reduced pressure
Microwave Assisted Plasma Deposition of
Silicon from the System SiCl4/H2
SiCl4 input: ≅1.74 mMol
Small silicon sinter for ignition
of plasma
Temperature: no visible glowing
Deposition takes place rapidlySiCl4 + 2 H2 → Si + 4 HCl
Yield of Si: ≅ 64% = 31 mg
Deposited Si is amorphous or
crystalline depending on the
temperature of the glass wall
Analysis of the Solid Product
Element Spect. Typ Weight % Atom %
O ED 8.74 14.44
Cl ED 1.55 1.15
Si ED 89.72 84.41
Under reduced pressure
Pressure: ≅ 2 kPa
SiF4/H2 ratio: ≅ 2/1 - 1/1
Duration: 15´
Microwave Assisted Plasma Deposition of
Silicon from the System SiF4/H2
Power input: 380 – 300 W
SiF4 input: ≅12 mMol
Small silicon sinter for
ignition of plasma
Temperature: no visible
glowing, but plasma
discharge
Deposition takes place
SiF4 + 2 H2 → Si + 4 HF
Yield of Si: ≅ 7% = 24 mg
Element Spect. Typ Weight % Atom %
O ED 0.45 0.79
F ED 1.06 1.56
Si ED 98.48 97.65
Analysis of Deposition Product
Pressure: ≅ 200 – 500 Pa
SiCl4/H2 ratio: ≅ 1/10 (saturated at RT)
Duration: 1 h
Under reduced pressure
Microwave Assisted Plasma Deposition of Silicon
from the System SiCl4/H2 at Low Power Input
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
Sample from the white region
Analysis of Deposited Solids: (Cl2Si)n
Sample from the brown region
Element Spect. Typ Weight % Atom %
O ED 9.96 18.39
Cl ED 59.88 49.89
Si ED 30.16 31.72
Element Spect. Typ Weight % Atom %
O ED 6.3 12.08
Cl ED 63.46 54.9
Si ED 30.23 33.02
City Solar Pilot Plant
0,01kg/a
1kg/a
~50kg/a
~1,0t/a
~10t/a
0,0001
0,001
1,0
10,0
0,00001
0,01
0,1New
Reactor-Typ
underconstruc-
tion
yearly production capacity[in tons]
Q4/2005 Q1/2006 Q4/2006 Q3/20070
Q2/2005
SiO2
SiCl4
Si
2
4 HCl
2 CO
+ 2 H2
2 CO
2 H2
4 HCl
2 H2
-SiCl4∆
(Cl2Si)n
Laboratory scale device for microwave assisted polysilane and silicon production
SiO2
SiF4
4 HF
2 H2O
O2
2 H2
4 HF
2 H2
-SiF4∆
(F2Si)n
Carbon Free Silicon Production
polysilane and silicon production
REM picture of silicon from the carbon free fluorine routePerfluorinated polysilane, (F2Si)n
∆T
Si
Combination of Processes ?
23500 t HSiCl3
deposition
4 HSiCl3 � Si + 3SiCl4 +2H2
1500 t H2
1000 t Si
5000 t MG-Si
Si + 3HCl� SiHCl3 +H2
chlorination, condensation, distillation
condensation
distillation
25000 t
23300 t
22000 t SiCl4
1300 t HSiCl3
1600 t H2
100 t H2pyrogenic silicic
acid (silica)
AEROSIL
Combination of Processes is a Simple Option !
23500 t HSiCl3
deposition
4 HSiCl3 � Si + 3SiCl4 +2H2
1500 t H2
1000 t Si
25000 t
~3600 t Si
10970 t SiCl4
+
~4600 t Si
40-340 t H2
condensation
distillation
23300 t
22000 t SiCl4
1300 t HSiCl3
1600 t H2
100 t H2
SiCl4 + H2 � SinCl2n + 2 HCl
plasma polymerisation
200-500 t H2
12800 t SinCl2n
thermolysis
2SinCl2n � Si + SiCl4
9460 t HCl
PV-Silicon SiCl4
SiCl4
Plasma-
Process
HCl
Pyrolysis
∼ 350 °CSi Cl ; Si Cl
perchlorinated
polysilanes
Facts and Perspectives
solid
SinCl2n; SinCl2n+2
H-Polysilanes (HPS)
HPS
CO2-Free Alternative Fuel
Si4Hn Si5Hn Si6Hn Si7Hn Si8Hn Si9Hn Si10Hn Si11Hn Si12Hn Si13Hn
Si14Hn Si15Hn Si16Hn Si18Hn
Octasilane
Octane
H-SILANE ÜBERTREFFEN DOE – TARGETS SIGNIFIKANT
20,35%
10%
15%
20%
25%
percent
HPS Surpasses DOE Targets Significantly
US-DOE-target State of the art HPS (20% H2)
R1
6,50%
4,50%
0%
5%
10%
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. %
Energieumsatz im Antriebsmotor pro eingesetzter Menge des Energieträgers
3,86
4,21
Benzin
Diesel
ener
gy
carr
ier
Combustion in an Diesel Engine
Combustion in an Otto Engine
Energy Output per 1 kg of
Energy Carrier in Driving Engines
3,52
3,36
2,21
0 0,5 1 1,5 2 2,5 3 3,5 4 4,5
HPS (20% H2)
HPS (20% H2)ener
gy
carr
ier
kWh/kg
Combustion in an Otto Engine
Hydrogen in a PEM Fuel Cell
Combustion: H2 HPS
Volumenbedarf von 10 kg gespeichertem Wasserstoff
249
417
CH2 (700 bar)
CH2 (350 bar)
Was
sers
toff
qu
elle
Hyd
rog
en s
ou
rce
Compressed hydrogen, 350 bar
Compressed hydrogen, 700 bar
Volume Required for Storage of 10 kg Hydrogen
71,4
200
50
143
0 50 100 150 200 250 300 350 400 450
HPS (20% H2)
LH2Was
sers
toff
qu
elle
Volumen [L]
compact System volume: material + empty space sphere packing + 4% functional layer on spheres
Liquid hydrogen ? System volume: material + empty space + insulation
Hyd
rog
en s
ou
rce
The ConceptThe Concept
Electricity H2problem:
low efficiency
problems:
• loss by transportation
• no long time storage
• immediate use required
problems:
• transportation
• storage
HYFORUM 2000: The energy carrier of the new century is hydrogenhydrogen
- availability, but no need
- need, but no availability
Water
Electrolysis
Renewable
Energy
problem: lack of H2O
• storage
• cost intensive infrastructure
• environment
Today´s need: - > 50Mio t/year
- > 90% petrochemistry
- < 7.5% H2O electrolysis
Statement of the Energy Departement, Washington DC, July 2002:… we are looking for „revolutionary“ new energy production schemes, being convincedthat „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 secondaryenergy 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 itis in plants through photosynthesis“.
Excess of
Need of EnergyRenewable Energy
C CO2 Si SiO2
E E
Proposed Long Term Solution
photosynthesis solar energy
Abundance C: 0,02 %
2 10-7 % (!)
26,3 % Si 56,4 % SiO2
•Organo-C:
CnH2n+2 SinH2n+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
SiliconH2O
(X Si)[H]
trzr
T /�(H Si)
H2O H
Transport
and
Storage
Water-
Electrolysis
(X2Si)n
[H]T /�
SiO2
Electricity and Water
SiX4
(H2Si)n
H2O H2
(X = Cl, F)
PEM Fuel Cell
• Wacker – Chemie GmbH
• Dow Corning Corporation
• City Solar AG
Acknowledgements
AK Prof. Norbert Auner
− Dr. Rumen Deltschew
• Coworkers
− Martin Bleuel
− Dr. Jens Elsner− 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)
− Dr. Jens Elsner
− Dr. Alireza Haghiri
− Andreas Hess
− Dr. Javad Mohsseni Ala
− Simon Nordschild
− Natalie Spomer
− Dr. Fariba Maysamy Tmar
− Dr. Yu Yang
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