Ion Implantation and Ion Beam Analysis of Silicon Carbide

Zsolt ZOLNAI

MTA MFA

Research Institute for Technical Physics and Materials Science Budapest, Hungary

University of Hyderabad4th October 2007

Outline

• SiC: physical properties and applications

• 3.5 MeV 4He+ ion backscattering spectrometry in combination with channeling

(BS/C)

• He+ implantation into SiC

• N+ implantation into SiC from channeling direction

• High dose Ni+ implantation into SiC

SiC: physical properties

CREE: 4H, 6H-SiC substrates

ESA: ultra-light weight mirrors

SiC: applications

ITER: first wall material

Infineon: Schottky diodes

SiC

Semiconductortechnology

Space applications

NuclearEnergetics

Other:spintronics, optoelectronics, etc.

Slow diffusion of dopants (below 2000 oC)

Selective doping by ion implantation

Generation of Crystal Defects

(vacancies, antisites, interstitials, extended defects, complexes)

Modification of the electrical properties

(Carrier trapping, detrapping)

SiC technology: selective doping

SiCp - type (Al, Ga, B)

n - type (N, P)

10-100 keV

SiC: polytypes

A site

B site

C site

C atom

Si atom

<0001>

<1100>

c-axis

A

B

A

B

C

A

B

C

2H-SiC3C-SiC

4H-SiC

6H-SiC

A

B

C

A

(1120)

3.5 MeV 4He+ Ion Backscattering Analysis on SiC

Favourable for Si and C sulattice

studies!

= 165o

4He+

The damaging effect of the analyzing He+ ion beam

saturation

N. Q. Khánh et al., Nucl. Instrum. Methods Phys. Res. B 161-163 (2000) pp 424-428

Electronic stopping power for channeled He+ ions along the [0001] axis of 6H-SiC: application in BS/C spectrum analysis

SeChannel = Se

Random

Crystal-TRIM simulation: = 0.8

Damage distributions in N+ implanted SiC(No thermal diffusion of defects expected)

BS/C spectrum analysis

Implantation of 500 keV N+ ions into 6H SiC: the influence of channeling on damage production

N+

6H-SiC

0001

axi

s Beam tilt angles:0o, 0.5o, 1.2o, 1.6o, 4o

Critical angle for channeling

CRIT = 1.7o

Beam tilting

Implantation of 500 keV N+ ions into 6H SiC: the influence of channeling on damage production

3.55 MeV 4He+ BS/C spectra RBX simulation of BS/C spectra

Tilt angles with respect to the [0001] axis: 0o, 0.5o, 1.2o, 1.6o, 4o

Implantation of 500 keV N+ ions into 6H SiC: the influence of channeling in damage production

0001 axis

N+

0001 axis

N+

Reduccd damagefor channeling

No surface defects:good for thedeterminationof the parameterfor He

Z. Zolnai et al., J. Appl. Phys. 101 (2007) 023502

Implantation of 500 keV N+ ions into 6H SiC: the influence of channeling in damage production

Crystal-TRIM simulationfor 500 keV N+ implant: SiCBS/C spectrum analysis

Z. Zolnai et al., j. Appl. Phys. 101 (2007) 023502

200 400 600 800 1000

1E-4

1E-3

0.01

0.1

1

Channeling peak

2.5x1014cm-2

7.5x1014cm-2

BS/C analysis Crystal-TRIM

1013cm-2

5x1013cm-2

Random peak

1.58x1015cm-2

Rel

ativ

e d

iso

rder

Depth (nm)

0001 axis

N+

Implantation of 500 keV N+ ions into 6H SiC: the influence of channeling in damage production

Dose dependenceof damage

Direct-impact, defect-stimulated (D-I/D-S) amorphization model

Implantation of 500 keV N+ ions into 6H SiC: the influence of channeling in damage production

Z. Zolnai et al., J. Appl. Phys. 101 (2007) 023502

S = fa + Sd = 1 − g(D) + Sd

max[1 − exp(− BD)]g(D)

and

g(D) = (a + s)/ (s + a exp [{a + s}D])

S: total disorderfa : amorphization in collision cascades Sd: point defect generation

a : direct impact amorphizationcross-section

s : defect stimulated amorphizationcross-section

Implantation of 500 keV N+ ions into 6H SiC: the influence of channeling in damage production

0.0

0.2

0.4

0.6

0.8

1.0 S = fa+S

d

Sd

fa

Rel

ativ

e S

i Dis

ord

er (

S)

0o

0.5o

1.2o

1.6o

4o

0.0 0.1 0.2 0.3 0.4 0.50.0

0.2

0.4

0.6

0.8

1.0 S = fa+S

d

Sd

fa

Rel

ativ

e C

Dis

ord

er (

S)

Displacements Per Atom (dpa)

500 keV N+: SiC 3.5 MeV He+: SiC

High-energy light ions:The direct impactamorphization isnegligible!(dilute collision cascasdes)

Diluted magnetic semiconductors: doping by transition metal ions (Fe, Co, Ni, Mn, Cr, V, etc.) for spintronics applications

Wide bandgap semiconductor high Curie temperature!

Doping with Mn, Fe, Co, Ni, Cr, V, etc

Carrier mediated ferromagnetism

Tested in GaAs, ZnO, GaN, ...

SiC is a possible candidate (bandgap is 3.26 eV for 4H polytype)

High dose 860 keV Ni+ implantation into 4H-SiC

100 200 300 400 5000

500

1000

1500

2000

2500

3000

3500

C

Si

c/a interface 770 nm in depth

Yie

ld

Channels

Virgin Random

1x1016 Ni+cm-2 (<11-20> SiC)

1x1016 Ni+cm-2 (<0001> SiC)

3x1016 Ni+cm-2 (<0001> SiC)

5x1016 Ni+cm-2 (<0001> SiC)

Ni

100 200 300 4000

500

1000

1500

2000

2500

3000

C

Si

Ni

Yie

ld

Channels

Random Aligned implanted annealed Virgin <11-20>

1x1016/cm2 (0001) SiC3x1016/cm2 (0001) SiC5x1016/cm2 (0001) SiC

1x1016/cm2 (11-20) SiC 1150 oC annealing, 1 h, in Ar atm.

High dose Ni+ implantation into 4H-SiC

4H-SiC (0001) 4H-SiC (11-20)

860 keV Ni implantation, 1x1016/cm2

1150 oC annealing, 1 h, in Ar atm.

Thank you for your attention!