Outline• Background

Si nanophotonics and an electro-optic device• Aerosol deposition (AD)• Dielectric properties of AD-PZT films• Objectives• Experimental results at SPring-8

-XAFS-Diffraction

High speed compared to thermo-optic and MEMS- Modulation over GHz.

Small size- <100 μm modulation length with high EO effect material.

High speed optical modulator with LSI scale– Electro-Optic modulator -

1.7mm

Modulation length

30 μm

・Small size 1/50・ Low driving voltage 1/50

LiNbO3： △n＝4.5×10-4PLZT（8/65/35）： △n＝0.025

Size estimation of 2 μm thick waveguide with 10V (E= 50kV/cm).

Fabrication process for large EO effect material- Aerosol Deposition (AD) -

Deposited powder ADImpact consolidation of nano particles

Grain diameter < 20 nmSubmicron particle

高速（300m/s)で粒子を基材に衝突させて、破砕、結合させます

Powder

AD film

Particle size 100~500 nm

Grain size < 20 nm

J. Akedo and M. Lebedev, Jpn. J. Appl. Phys. 38, 5397 (1999).

Film formation with nano-particles by ADFilm formation with nano-particles by AD

Low cost process

Deposition machine

PLZT film: perovskite structure

20 nm

Crystal structures remain during film formation.

High quality EO (complex oxide) films over μm-thickness can be deposited on Si and any kind of substrates / films.

AD advantage in optical device fabrication process

Sputtering, Sol-gel, LA CVD, MBE, ,EB-evaporation

Atom / cluster

AD

Reconstruction of crystal lattices by under layer and high temperature.

Submicron particle

High performance electro-optic oxide film on glass substrate.

LiNbO3

AD-PZT film

Electro-optic effect

X 6

・Electro-optic effect 102 pm/V

・Transmittance less 1.7 dB/mm

Issues of AD film formation・Increase of EO effect

-Bulk EO effect: ~300 pm/V -AD film EO effect: ~100 pm/V

・Annealing

Dielectric properties of AD-Pb(Zr0.3Ti0.7)O3 films

0

0.002

0.004

0.006

0.008

0.01

0 50 100 150 200

E (kV/cm)

δ△

ｎ

600oC

500oC

As-deposited0

200

400

600

800

0 200 400 600 800

Annealing temparature

Die

lect

ric c

onsta

nt

Dielectric constant EO effect

-40

-30

-20

-10

0

10

20

30

40

-400 -300 -200 -100 0 100 200 300 400

電界E[kV/cm]

分極

値P

[μC

/cm

2]

Polarization600oC

400oC

As-deposited

As-deposited film: poor400oC: moderate,

but poor ferroelectric600oC: ferroelectric

0

0.1

0.2

0.3

0.4

20 30 40 50２θ(deg）

Rel

ativ

e in

tens

ity

0

0.1

0.2

0.3

0.4

20 30 40 50２θ(deg）

Rel

ativ

e in

tens

ityStarting powderAs-deposition film

(100)

(110)

(111)(200)

(210)

Starting powder600oC annealing

800oC annealing

X-ray diffraction patterns of AD-Pb(Zr0.6Ti0.4)O3

Broadening peak widths

Large bump at about 30o

Peak shift to lower angle

Sharpening peak widths

Disappearance of the bump

Disappearance of

the peak shift

AD process

Annealing process

Strain, lattice defect and/or reduction of grain size

XAFS measurement of PbTiO3 ,Pb(Zr0.3Ti0.7)O3

SPring-8 B16B2 (Sun beam)Measurement of powders, as-deposited AD films and annealed AD films

Transmission: Pb-LIII, Zr-K

Florescence: Ti-K

9.00E-01

9.50E-01

1.00E+00

1.05E+00

13000 13050 13100 13150 13200 13250 13300

E (KeV)

mXAFS spectra of Pb－LIII of PbTiO3

・Change of XAFS spectrum with AD film formation ・Recovering with annealing

0.00E+00

5.00E-01

1.00E+00

1.50E+00

2.00E+00

2.50E+00

0 1 2 3 4 5

R (A)

k3ch

i

XAFS spectrum FT of the Pb XAFS spectra

Powder

AD-as-depositedAD-annealed

Pb(Zr0.3Ti0.7)O3

0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

1.40E+00

1.60E+00

4960 4970 4980 4990 5000 5010

E (eV)

mu

9.00E-01

9.20E-01

9.40E-01

9.60E-01

9.80E-01

1.00E+00

1.02E+00

1.04E+00

13000 13050 13100 13150 13200 13250 13300

E (eV)

m

Pb-LIII

Ti-K

Powder

AD-as-deposited

AD-annealed

6.00E-01

7.00E-01

8.00E-01

9.00E-01

1.00E+00

1.10E+00

1.20E+00

1.30E+00

1.40E+00

1.50E+00

17980 18000 18020 18040 18060 18080 18100

E (eV)

m

Zr-K

・Change of XAFS spectrum with AD film formation

・Recovering with annealing

0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

1.40E+00

1.60E+00

4960 4970 4980 4990 5000 5010

E (eV)

mu

Ti-K

AD film formation affect on Ti configurations.

XANES spectra of Ti-K

28.5

29

29.5

30

0 0.2 0.4 0.6 0.8 1

sin2χ

2θ

(deg)

As-deposited

Annealed

0.01

0.1

1

27 28 29 30 31

2θ (deg)

Inte

nsi

ty

χ70o

χ0o

Residual stress measurement of AD-PZT films

SPring-8 B16XU (Sun beam)Diffraction pattern measurement with incidental angle to the film surface χ.

Diffraction pattern of the annealed AD film with χ Sin2χ vs. 2θ

220 MPa-630 MPaResidual stress

AnnealedAs-deposited ・The uniform residual stress can be reduced by annealing

Summary• Short range ordering of PZT films is damaged by AD

film formation. • AD film formation damage is practically recovered

by annealing.• The uniform residual stress can be reduced by

annealing

AcknowledgementsThis research was partially supported by the NEDO project for “Nano Structure Formingfor Advanced Ceramic Integration Technology in Japan’s nano technology program”.