Nano Structures and Dynamics Lab., MSE, NTHU Self-Assembled Nanostructures Mediated by Gold Particles Lih J. Chen Department of Materials Science and Engineering,

Nano Structures and Dynamics Lab., MSE, NTHU

Self-Assembled Nanostructures Mediated by Gold Particles

Lih J. Chen

Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan


Nano = “dwarf” in Greek




J. Heath, L-09, School on Nanomechanics, Hawaii (2002).


Nature, 419, 553 (2002).


1D nanostructures

• to provide a good system to investigate the dependence of electrical and thermal transport or mechanical properties on dimensionality and size reduction• to play an important role as both interconnects and functional units in fabricating electronic, optoelectronic, electrochemical, and electromechanical devices with nanoscale dimensions



micro- (cells) and nanostructure (wax crystals)


Opal ( 蛋白石 )與其奈米結構


蝴蝶翅膀與其奈米結構


Small-sized Au catalysis has attracted increasing interest because of the discovery of extraordinary catalytic activity and specificity.

Au nanoparticles consisting of metal inner-core and organic outer-shell can be acquired as the nanostructured catalysts from size controllability, monodispersity, processibility, and aggregation resistivity.

Self-assembled honeycomb networks of Au nanoparticles show promise as the regular patterns for the growth of various nanowires without complex lithography.

Introduction


Two-phase Method (Au@TOAB)

Stirrer plate

Phase-transfer reagents(C8H7)4NBr

Reduction reagent

(NaBH4)

HAuCl4·3H2O (aq.)Stirring rod


Au@TOAB

R= C8H17R’= C12H25

Au@TOAB-DT

N

R

RR

R Br

Au

N

R

RR

R Br

NR

R R

RBr

N R

R RR

Br

NRRR

RBr

NR

RR

RBr

NR

RRR

Br

NR RR

RBr

Au

S

R’

S

R’

S

R’

SR’

S

R’ S

R’

S

R’

S R’

S

R’S

R’

S

R’S

R’

S

R’

S

R’

S

R’ S

R’

TOAB desorption

DT adsorption

Displacement Reaction of Outer-Shells


Displacement Reaction of Outer-Shells

TOAB desorption

DT adsorption

Au@TOAB Au@TOAB-DT


Au@TOAB-DT

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.00

10

20

30

40

50

average diameter = 4.9 nm

Fre

qu

enc

y

Diameter (nm)

std dev. 0.27nm


Drying Pattern

Si substrate/Cu/Al

Controlled temperature

Si substrate/Cu/Al

Controlled temperature


Self-assembled honeycomb networks (as-cast)Self-assembled honeycomb networks (as-cast)


800 ℃Back

Nano Structures and Dynamics Lab., MSE, NTHU400-1000-1000 0C, 30 min


400-1000 0C, 30 minP.Y. Su et al. Appl. Phys. Lett.

84, 3480 (2004).

Nano Structures and Dynamics Lab., MSE, NTHU1100 0C, 30 min




1100 ℃Back

Nano Structures and Dynamics Lab., MSE, NTHUNano Structures and Dynamics Lab MSE NTHU

950 -60 min℃ 1050 -60 min℃1000 -75 min℃

1080 -60 min℃



氧化矽奈米線與其對應陰極發光圖




at %

O 70.33

Si 24.12

Au 5.55

at %

O 39.94

Si 33.36

Au 26.7

EDS Analysis




TEM observationTEM observation

100 nm1 µm

100 nm

100 nm

Si substrate 100-nm-thick oxide


100 nm

0 5 10 15 20

O

Si

Cu

0 5 10 15 20

OSi

Cu

AuAu

EDS analysis


As cast 200 - 950 ℃ 1000 ℃

1100 ℃


thin oxide ~10 nm

Au-O compound

oxide~10 nm

Si

Si


thick oxide ~100 nm

Au-O compound

Si

Si

SiO2

SiO2

oxide~100 nm


SiOx decomposed

Si

Au AuAu

Ⅰ100-nm-thick thermal oxide layer

Au-Si-O liquid alloy

SiⅡ

Ⅲ

a. VLS growth mechanism

Vapor source

1.

2.Si(s) + SiO2(s) 2SiOx(g)

SiOx(L) SiOx(g)

b. Oxide-assisted growth mechanismSiOx vapor

SiOx wireFeature:

high-purity nanowires

without the need of a metal catalyst

Adv. Mater. 15, 635 (2003)

Si

flower-like structure


Si

Nano Lett., 3, 1317 (2003)： Au particle

： ZnO nanorod


P. Yang et al.J. Am. Chem. Soc. 125, 4728 (2003)

Dynamics and Nanostructures Lab.Dynamics and Nanostructures Lab.

ZnO Nanolasers: What on Earth?

Z. L. Wang et al. Nano Lett. 2004, 4, 423.

★ ZnO Dendritic Array

★ ZnO nonorods

Power-dependent PL spectra

Angle-dependent PL spectrasubstrate

Excitation light

Light emission

ZnO nanorods


Growth of ZnO nanowires


★1D ZnO arrays were synthesized at 800 ℃ -1100 for 90 min.℃


PL Spectrum of ZnO Nanolasers

340 360 380 400 420 440

386 nm

Annealing Temperature (℃)

PL

In

ten

sity

(ar

b. u

nit

)


★ Patterned Au nanodots by AFM

0 10 20 nm

m

★★ Substrate: ZnO/Si or Al2O3

substratesubstrate

0 4 8 nm

m


Patterned ZnO Lasers by SPLPatterned ZnO Lasers by SPL★ working pressure: 2.7 torr ★ working pressure: 2.7 torr


ZnS Nanorods


Au/Sapphire


Si/Au/Sapphire


Si/Au/Sapphire


Si/Au/Sapphire


Si/Au/Sapphire


Vapor transport process:Vapor transport process: self-organized Au particles on Alself-organized Au particles on Al22OO3 3 substrate - 9substrate - 9

10 10 00C, Si source- 1200 C, Si source- 1200 00C, Ar carrier gas 50 sccm, 2hr+3hr+5hrC, Ar carrier gas 50 sccm, 2hr+3hr+5hr

AlAl22OO33 Zone axis [1,-1,0] Zone axis [1,-1,0]

[0,0,6][0,0,6]

[1,1,1][1,1,1][1,-1,1][1,-1,1]

[0,2,0][0,2,0]

Au Zone axis [1,0,-1]Au Zone axis [1,0,-1]

Au Zone axis [1,0,-1]Au Zone axis [1,0,-1]

AlAl22OO33 Zone axis [1,-1,0] Zone axis [1,-1,0]

[1,1,1][1,1,1]

[0,0,6][0,0,6]

Au (1,1,1) //Au (1,1,1) //AlAl22OO33 (0,0,6) (0,0,6)

Au (0,2,0)Au (0,2,0)d = 0.204 nmd = 0.204 nmAlAl22OO33 (1,1,3) (1,1,3)d = 0.208 nmd = 0.208 nmEpitaxy ???Epitaxy ???


11

22

33

Vapor transport process:Vapor transport process: self-organized Au particles on self-organized Au particles on AlAl22OO3 3 substrate - 910 substrate - 910 00C, Si source- 1200 C, Si source- 1200 00C, Ar carrier gas C, Ar carrier gas

50 sccm, 2hr+3hr+5hr50 sccm, 2hr+3hr+5hr


1

2

3


100 nm


50 nm


Vapor transport process:Vapor transport process: self-organized Au particles on Si (111)self-organized Au particles on Si (111)substrate - 910 substrate - 910 00C, Si source- 1200 C, Si source- 1200 00C, 2 hr, Ar carrier gas 50 sccmC, 2 hr, Ar carrier gas 50 sccm


(a) (b)

Si source, 900 0C


0 1000 2000 3000 40000

1

2

3

4

5

6

7

Dis

pla

cem

ent

(A)

Time (fs)

Fig. 1 (a) Model structures of Au nanocluster (with 68 Au atoms) after 900 Fig. 1 (a) Model structures of Au nanocluster (with 68 Au atoms) after 900 00C, 1601 3C, 1601 3fs-time steps (4.8ps) simulated annealing. (b) Displacement curves of Au atoms durfs-time steps (4.8ps) simulated annealing. (b) Displacement curves of Au atoms during the 900 ing the 900 00C simulated annealing.C simulated annealing.

The surface diffusion speed can be as high as 100 m/sec at 900 The surface diffusion speed can be as high as 100 m/sec at 900 00C.C.

Simulation results : the initial model structure of Au fcc clusterSimulation results : the initial model structure of Au fcc cluster


0 1000 2000 30000

1

2

3

4

5

6

7

8

9

Dis

pla

cem

ent

(A)

Time (fs)

Fig. 2 Atomic structures of four SiO molecules initially absorbed on the Au nanoclFig. 2 Atomic structures of four SiO molecules initially absorbed on the Au nanocluster (with 68 Au atoms) surface (a) and after 1001 time steps (3ps) simulation (b).uster (with 68 Au atoms) surface (a) and after 1001 time steps (3ps) simulation (b). (c) Displacement curves of Au (black), and Si-O (color) atoms during the 900 (c) Displacement curves of Au (black), and Si-O (color) atoms during the 900 00C siC simulated annealing.mulated annealing.

Simulation result : the interaction of SiO vapor with Au particleSimulation result : the interaction of SiO vapor with Au particle

None of the SiO molecules was found to diffuse into Au cluster.None of the SiO molecules was found to diffuse into Au cluster.

The SiO molecules exhibit higher surface diffusion speed than Au atom. The SiO molecules exhibit higher surface diffusion speed than Au atom. After absorbing the SiO molecules, the surface diffusion speed of Au atom decrAfter absorbing the SiO molecules, the surface diffusion speed of Au atom decrease.ease.


0 1000 2000 30000

1

2

3

4

5

6

7

8

9

10

11

Dis

pla

cem

ent

(A)

Time (fs)

Fig. 3 Atomic structures of four Si atoms initially absorbed on the Au nanoclusteFig. 3 Atomic structures of four Si atoms initially absorbed on the Au nanocluster (with 68 Au atoms) surface (a) and after 1001 time steps (3ps) simulation (b). r (with 68 Au atoms) surface (a) and after 1001 time steps (3ps) simulation (b). (c) Displacement curves of Au (black), Si (color) atoms during the 900 (c) Displacement curves of Au (black), Si (color) atoms during the 900 00C simulatC simulated annealing.ed annealing.

Simulation result : the interaction of Si vapor with Au particleSimulation result : the interaction of Si vapor with Au particle

Si atoms absorbed onto the Au surface would intermix with Au atoms.Si atoms absorbed onto the Au surface would intermix with Au atoms.


Self-organized Ag particle network



Nano Structures and Dynamics Lab., MSE, NTHUTFP + water, rapid evaporation

Nano Structures and Dynamics Lab., MSE, NTHUNanoparticle Network


Thickness Dependence MorphologyThickness Dependence Morphology

FESEM images with the same magnifications of different spin-coated speed shown as follows (a) 1000rpm (b) 2200rpm (c) 3100rpm (d) 3800rpm (e) 4300rpm (f) 5200rpm (g) 6400rpm (h) 7100rpm (g) 8300rpm, respectively

100nm

100nm

100nm

100nm

100nm

100nm

100nm

100nm

100nm

(a) (b) (c)

(d) (e) (f)

(g) (h) (i)

Self-Assemble Diblock Copolymer

18nm

36nm

1μm

Two fabrication methods: Diblock copolymer& nanosphere


1μm 1μm

Polystyrene Nanospheres

1μm

1μm

10μm

1μm

Evaporation DepositionEvaporation Deposition Sputtering CoatingsSputtering Coatings


10μm

1μm

Size-Tunable Platinum Nanoparticles

100nm 100nm 100nm 100nm

As-sputtered Image As-annealed Image


1μm100nm

Low and high magnification SEM images of nickel disilicidearray formed by electron beam evaporation after annealing theNi at 900 . ℃

Chemical oxide

Another approach: ion implantation and solid phase epitaxy

Sioxide

Ge ionSPE and oxide removal Periodic nanometer scale

stress filed template


Growth of nanostructures on Si and Si1-xGex/(001)Si heterostructures


Growth of Si-Ge oxide nanowires

Nano Structures and Dynamics Lab., MSE, NTHUAu particles on Si0.8Ge0.2, 1140 0C, 30 min


300 400 500 600 700 800

SiGeONWs SiONWs

Wavelength (nm)

PL

In

ten

sity

(ar

b. u

nit

)470 nm

415 nm

Si and Si1-xGex substrates annealed 1140 ℃ for 1h

PL measurement of Si and Si1-xGex oxide nanostructures


PL Spectra of SiGeONWs at Different Annealing Temperature

950 1000 1050 1100 1150 12000

100

200

300

400

500

600

700

Annealing Temperature (℃)

PL

Pea

k W

avel

engt

h (n

m)

PL

Pea

k in

ten

sity

( a

.u.)

Annealing temperature↑, Density of NWs↑, PL peak intensity↑.PL peak position towards the longer wavelength slightly.


ConclusionsConclusions

1. Self-assembled growth of hexagonal Au or Ag particle networks on a variety of substrates (Si, SiOx, Si-Ge, Si3N4, Al2O3, MgO) has been achieved

2. The presence of an oxide layer at the Au/Si interface stabilizes the Au particles at the intersections at a temperature as high as 1000 ℃.



3. The cell and particle size can be adjusted from 200 nm-12 m and 20-400 nm, respectively

4. A wealth of novel nanostructures (SiOx, Si and ZnO nanowires, Cu nanoparticles) can be grown on the templates



5. The network provides a convenient template for the preparation of other functionalized materials (SH-group) for a variety of applications

6. The template with its distinct structure shall permit the monitoring of changes occurred on individual particles, which may leads applications such as molecular sensing

7. The growth mechanisms of nanostructures can be elucidated by in-situ TEM


Acknowledgments

P.Y. Su, J.C. Hu, J.H. He, T.F. Chiang, J.H. Wang (MSE, NTHU)J.M. Liang (NDL, NSC)M. Huang, T.C. Kwo (Chem, NTHU)S.L. Cheng (CMS, NCU)NSC, MoE

Documents

Nano Structures and Dynamics Lab., MSE, NTHU Self-Assembled Nanostructures Mediated by Gold Particles Lih J. Chen Department of Materials Science and Engineering,