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