Conformal nanocoatings for energy and electronics by …... 2 Atomic layer deposition (ALD) • Gas-phase thin film deposition technique • Cyclic process of self-limiting surface

Conformal nanocoatingsfor energy and electronics

by Atomic Layer Deposition

Christophe Detavernier

CoCooN group – Ghent University

CoCooNConformal Coating of Nanomaterials

www.cocoon.ugent.be 2

Atomic layer deposition (ALD)

• Gas-phase thin film deposition technique

• Cyclic process of self-limiting surface reactions layer-by-layer growth

Example :ALD growth of Al2O3

from trimethylaluminum (TMA) and H2O

TMA pulse Self-saturatedchemisorption

One (sub)monolayer of Al2O3

New OH groups at the surfaceWater pulse


Atomic layer deposition (ALD)

Self-saturating surface reactions enable

- Atomic level thickness control

- Conformal deposition onto 3D surfaces


ALD is ideal for coating at the nanoscale

TiO2/V2O5/TiO2 multilayer coating of a carbon nanotube

Advantages of ALD

▪ Atomic level thickness control

▪ Conformal deposition 3D substrates

▪ Excellent control of stoichiometry

▪ Highly uniform

▪ Easily upscalable

Limitations of ALD

▪ Slow – limited to nanocoatings and surface engineering


Advantages and limitations of ALD

Layer-by-layer deposition

Growth rate per cycle from linear fit

0.85 Angstrom/cycle

0 50 100 150 200

0

50

100

150

50 52 54 56 58 60

36

38

40

42

44

Th

ickn

ess (

An

gstr

om

)

Cycle number


Applications of ALD

• Electronics

• Functional nanocoatings in micro-electronics

• Coatings in photovoltaics

• Encapsulation of (O)LEDs

• Energy applications

• Coating of battery materials

• Coating nanoporous materials for catalysis

Since 2007: ALD crucial for high-k gate oxides

ALD is a key technology for micro-electronics

Market forecast from presentation by ASM

http://www.asm.com/images/stories/products/himg_ci79.jpg


Applications of ALD

• Electronics







ALD for passivation of solar cells

B. Hoex et al, Appl. Phys. Lett. 89, 042112 (2006)

Beneq

Upscaling of ALD reactors – batch reactors

2000 wafers / hour

Spatial ALD

www.cocoon.ugent.be

Dedicated reactor concepts for spatial ALD

4500 wafers / hour

Dedicated reactor concepts for spatial ALD


Applications of ALD

• Electronics







ALD for encapsulation of OLEDs

S. H. K. Park et al., Electrochem. Solid-State Lett., 8, H21 2005.M.D. Groner et al., Appl. Phys. Lett., 88, 051907 2006.


J. Meyer et al., Appl. Phys. Lett., 94, 233305 2009.

www.cocoon.ugent.be


19

ALD nanocoatings for encapsulation:Protecting CaS:Eu phosphor powders from moisture

Avci et al., J. Electrochem. Soc. 156(11) J333 (2009).


Applications of ALD

• Electronics







ALD for improving battery materials

➢ Ultra thin protective coatings on electrode materials

➢ Enhancing cyclability Li ion batteries

Cavanagh et al. (2009)

Myung et al (2011)

ALD for improving battery materials

Forge Nano

~ $2/kg for 2 ALD cycles Al2O3 on LCO

Now : 30 & 300-ton/year plant.

Planned: 3,000-ton/year plant


Applications of ALD

• Electronics







ALD for catalysis and filtration

ALD in micro-electronicsAspect ratio = 1/1 - 1/100

ALD inside nanoporous materialsAspect ratio = 1/1.000 – 1/10.000

Deposition onto pore walls

Catalysis,fuel cells

Controlling pore size distribution

Molecular filtration,membranes

www.cocoon.ugent.be

ALD coating of nanoporous materials for catalysis

ALD coating throughout the interior surface of a nanoporous material

• ALD of amorphous TiO2 inside mesoporous silica particles

• Calcination leads to uniformly distributed anatase TiO2 nanoparticles

C-ALD Meeting 2014, Shanghai 26

Photocatalysis

S.P. Sree, J. Dendooven, K. Masschaele, H.M. Hamed, S. Deng, S. Bals, C. Detavernier, J.A. Martens, Nanoscale, 2013,5, 5001-5008

C-ALD Meeting 2014, Shanghai 27

Photocatalysis

S.P. Sree, J. Dendooven, K. Masschaele, H.M. Hamed, S. Deng, S. Bals, C. Detavernier, J.A. Martens, Nanoscale, 2013,5, 5001-5008

0 1 2 3 4

0.0

0.2

0.4

0.6

0.8

1.0

Porous film - 0 ALD cycles

Porous film - 50 ALD cycles

Glass - 2200 ALD cycles

Me

thyle

ne

blu

e C

(t)/

C0

irradiation time (h)

• Excellent dispersion of anatase particles in accessible mesopores

• Excellent photocatalytic activity

• Method can be extended to other metal oxides

• Potentially useful concept for lab-on-a-chip applications

www.cocoon.ugent.be

ALD reactors concepts for coating powders

Fluidized bed reactor (FBR)

Delphine Longrie et al., J. Vac. Sci. Technol. A 32(1), Jan/Feb 2014

Rotary reactor

CoCooN


FUNC

FUNC:Tools for dry nanofunctionalization of

particles and fibrous materials

http://www.vub.ac.be/


ALD on powders

D. Longrie et al., Surface and Coatings Technology, 213 (2012) 183.

Geldart diagram


Summary

• Atomic layer deposition offers• Ultimate thickness control• Ultimate conformality

• Wide range of applications in Electronics• Micro-electronics – gate oxides (since 2007) & more …• Passivation of solar cells• Encapsulation of (O)LEDs

• Wide range of applications in Energy• Enhancing battery materials through nanocoatings• Coating nanoporous materials for catalysis

• Dedicated reactor designs required for specific applications• ALD is being explored for powder coating within SIM-FUNC


ACKNOWLEDGEMENTS

Documents

Conformal nanocoatings for energy and electronics by …... 2 Atomic layer deposition (ALD) • Gas-phase thin film deposition technique • Cyclic process of self-limiting surface