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 Hyderabad 4 th October 2007

Outline SiC: physical properties and applications 3.5 MeV 4 He + 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 Semiconductor technology Space applications Nuclear Energetics Other: spintronics, optoelectronics, etc.

Slow diffusion of dopants (below 2000 o C) 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 SiC p - type (Al, Ga, B) n - type (N, P) keV

SiC: polytypes A site B site C site C atom Si atom c-axis A B A B C A B C 2H-SiC 3C-SiC 4H-SiC 6H-SiC A B C A (1120)

3.5 MeV 4 He + Ion Backscattering Analysis on SiC Favourable for Si and C sulattice studies!  = 165 o 4 He +

The damaging effect of the analyzing He + ion beam saturation N. Q. Khánh et al., Nucl. Instrum. Methods Phys. Res. B (2000) pp

Electronic stopping power for channeled He + ions along the [0001] axis of 6H-SiC: application in BS/C spectrum analysis S e Channel =  S e 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+N+ 6H-SiC 0001 axis Beam tilt angles: 0 o, 0.5 o, 1.2 o, 1.6 o, 4 o Critical angle for channeling  CRIT = 1.7 o Beam tilting

Implantation of 500 keV N + ions into 6H SiC: the influence of channeling on damage production 3.55 MeV 4 He + BS/C spectraRBX simulation of BS/C spectra Tilt angles with respect to the [0001] axis: 0 o, 0.5 o, 1.2 o, 1.6 o, 4 o

Implantation of 500 keV N + ions into 6H SiC: the influence of channeling in damage production 0001 axis N+N+ N+N+ Reduccd damage for channeling No surface defects: good for the determination of the  parameter for He Z. Zolnai et al., J. Appl. Phys. 101 (2007)

Implantation of 500 keV N + ions into 6H SiC: the influence of channeling in damage production Crystal-TRIM simulation for 500 keV N + implant: SiC BS/C spectrum analysis Z. Zolnai et al., j. Appl. Phys. 101 (2007)

0001 axis N+N+ Implantation of 500 keV N + ions into 6H SiC: the influence of channeling in damage production Dose dependence of 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) S = f a + S d = 1 − g(D) + S d max [1 − exp(− BD)]g(D) and g(D) = (  a +  s )/ (  s +  a exp [{  a +  s }D]) S: total disorder f a : amorphization in collision cascades S d : point defect generation  a : direct impact amorphization cross-section  s : defect stimulated amorphization cross-section

Implantation of 500 keV N + ions into 6H SiC: the influence of channeling in damage production 500 keV N + : SiC3.5 MeV He + : SiC High-energy light ions: The direct impact amorphization is negligible! (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 1x10 16 /cm 2 (0001) SiC 3x10 16 /cm 2 (0001) SiC 5x10 16 /cm 2 (0001) SiC 1x10 16 /cm 2 (11-20) SiC 1150 o C annealing, 1 h, in Ar atm.

High dose Ni + implantation into 4H-SiC 4H-SiC (0001) 4H-SiC (11-20) 860 keV Ni implantation, 1x10 16 /cm o C annealing, 1 h, in Ar atm.

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