Fabrication of Silicon Nanocones Using Fabrication of Silicon Nanocones Using RF Microplasma Jet at Atmospheric PressureRF Microplasma Jet at Atmospheric Pressure

18th SYMPOSIUM ON PLASMA SCIENCE FOR MATERIALS (SPSM-18)

○○ Zhongshi Yang

Research Background Micro-analysis of the Cone Structures Mechanism of the SNC Growth Conclusions

背景

Synthesis of silicon and carbon Synthesis of silicon and carbon nanostructuresnanostructures

Research Background

field emission devices, UV laser, FET, sensors

RF microplasma jet at atmospheric pressure on Fe coated c-Si using a CH4-Ar mixture

CNTs 　　 Nanocones 　　　 　Nanopillars

CVD, laser ablation, RIE, electrodeposition

RF power13.56MHz

Gas

TTss

MatchingNetwork

d

ＤOES

Pump

ArAr

CHCH44

ＨＨ２２

CHCH44 c-SiFe

CHCH44Ar Plasma

Fabrication ConditionsFabrication Conditions

Cathode: WC tube with d of 700 µm

Substrate: Fe coated c-Si

Fr(Ar):50sccm Fr(CH4) :50 sccm

D : 4 mm Ts:400ºC RF power:40W

The inner diameter of The inner diameter of Electrode Electrode : 700 µm: 700 µm

400400μμ mm

600600μμ mm

10001000μμ mm

A A 領域領域

C C 領域領域

B B 領域領域

400400μμ mm

600600μμ mm

10001000μμ mm

A A 領域領域

C C 領域領域

B B 領域領域CHCH44

: 400: 400～～600600μμ mm : 600: 600～～800 μμ m m BB CC

１００ｎｍ １００ｎｍ

SEM Image

１．５１．５ μμ ｍｍ

AA　　　　　　 : : 400μm400μm

SiSiOO

5μ5μmm

Surface Distribution of elementsSurface Distribution of elements

EDX SpectraEDX Spectra

SEMSEM ImageImage

0

1000

2000

3000

4000

5000

6000

0 0.5 1 1.5 2

X r

ay

in

ten

sity

(a

rb.u

nit

)

X ray Energy (eV)

Si

O

5μ5μmm

5μ5μmm

CC FeFe

5μ5μmm

5μ5μmm

SSilicon ilicon nanonanoconecones (SNCs)s (SNCs)

Come-shaped products were mainly

composed of silicon and SiO2.

SNCSNCA A regionregion

60 nm60 nm

B B regionregion

CNTCNT

SNWsSNWs

67nm67nm

20nm20nm

14nm14nm

SiSi

11μμmm11μμmm

EDX analysis

Si nanocrystals are embedded in the cone region

500 1000 1500 2000

-2000

0

2000

4000

6000

8000

10000

12000

Hei

ght (

nm

)

Ar+CH4 plasma

Distance (m)Distance (m)

Hei

gh

t (n

m)

500 1000 1500 2000-1000

-500

0

500

1000

1500

2000

2500Ar plasma

Linear Surface ProfileLinear Surface Profile

CHCH44 introduction and Fe film are very introduction and Fe film are very

important to the SNCs growthimportant to the SNCs growth..

(a) (a) Ar & Ar+CHAr & Ar+CH44 plasma plasma c-Si etched hole c-Si etched hole & no cones& no cones (b) (b) ArAr plasma plasma Fe/c-Si Fe/c-Si 　 　 etched holeetched hole & no cones& no cones

(c) (c) Ar+CHAr+CH44 plasma plasma Fe/c-Si SNCs, SNWs, CNTsFe/c-Si SNCs, SNWs, CNTs

plasma plasma substrate results substrate results

Fe/c-Si surface

② 照射時間依存

1min1min

30min30min 60min60min

10min10min

・・ Number density increasedNumber density increased

・・ Average size increasedAverage size increased

１１ μmμm

１１μmμm

１１ μmμm

１１ μmμm

HH

RR

0

1

2

3

4

5

6

0

0.2

0.4

0.6

0.8

1

0 10 20 30 40 50 60 70

H (μm) R

(μm)

Plasma exposure time (min)

Growth Model of SNCs

Ar plasma jet

~20 nm thick Fe layer

1 High gas temperature (2000-3000K) of Ar microplasma jet.

2 Formation of FeSix and FeCx nanoclusters.

3 Catalytic growth by a diffusion of Si and nanocrystalline silicon particles through the FeSix nanoclusters.

4 Silicon oxidation at the outer walls by the plasma heating.

CH4

Tg: 2000 ～ 3000K

c-Si

CH4

nc-Si particleSi oxidation

Si Nanocones (SNCs) were synthesized on Fe-coated c-Si using RF microplasma jet at atmospheric pressure.

18th SYMPOSIUM ON PLASMA SCIENCE FOR MATERIALS (SPSM-18)