ion implantation and ion beam analysis of silicon carbide zsolt zolnai mta mfa research institute...
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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
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.