Investigation of C[sub x]Si defects in C implanted silicon by transmission electron microscopy (original) (raw)
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Spectroscopic characterization of phases formed by high-dose carbon ion implantation in silicon
Journal of Applied Physics, 1995
High-dose carbon-ion-implanted Si samples have been analyzed by infrared spectroscopy, Raman scattering, and x-ray photoelectron spectroscopy (XPS) correlated with transmission electron microscopy. Samples were implanted at room temperature and 500 "C~with doses between lOI7 and 10's C+/cm'. Some of the samples were implanted at room temperature with the surface covered by a capping oxide layer. Implanting at room temperature leads to the formation of a surface carbon-rich amorphous layer, in addition to the buried implanted layer. The dependence of this layer on the capping oxide suggests this layer to be determined by carbon migration toward the surface, rather than surface contamination. Implanting at 500 "C, no carbon-rich surface layer is observed and the Sic buried layer is formed by crystalline /!-Sic precipitates aligned with the Si matrix. The concentration of SIC in this region as measured by XPS is higher than for the room-temperature implantation. 0 1995 American Institute sf Physics.
High temperature annealing effects on the electrical characteristics of C implanted Si
Journal of Applied Physics, 1996
We have investigated the electrical characteristics of p ϩ -n Si junction diodes implanted with 300 keV C ions at fluences of 0.5 and 1ϫ10 15 cm Ϫ2 and annealed at 900 or 1100°C. In all cases cross-sectional transmission electron microscopy shows an excellent crystalline quality, with no extended defects, and the C-rich region is characterized by an n-type doping. In the material annealed at 900°C the C-rich region shows a low electron mobility and the presence of deep donor levels, and, as a consequence, the diode characteristics are nonideal. These effects can be attributed to the formation of C-Si self-interstitial-type complexes after the 900°C anneal. At 1100°C part of the C-Si complexes dissolve and the electrical characteristics of the materials noticeably improve.
Ion implantation effects in silicon with high carbon content characterised by photoluminescence
Physica B: Condensed Matter, 2003
The evolution with annealing of defects in self-ion implanted silicon with high carbon content has been investigated by photoluminescence (PL). The PL spectra show that the high-content carbon can effectively prevent the formation of {1 1 3} self-interstitial aggregates defect in silicon of implant dose 10 13 and 10 14 cm À2 and largely suppress the formation of {1 1 3} defect at higher implant doses. By trapping and storing the excess interstitials a variety of stable carbonrelated clusters are formed, which could persist to quite high annealing temperature. The strong asymmetry of the PL band near 910 meV, with a long tail on the high-energy side, may originate from the size distribution of Ostwald ripening carbon-related clusters.
MeV carbon implantation into silicon: microstructure and electrical properties
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1992
Doping effects after carbon implantation at 0 .33 and 10 MeV were investigated at silicon wafers with different oxygen content. No distinct influence of the oxygen concentration on the carbon induced doping effect was found for rapid thermal annealing at 1250°C for 30 s whereas for furnace annealing at 1000°C the doping effect is higher for Czochralski-grown silicon wafers with their higher oxygen content. The gettering efficiency of a buried carbon implanted layer for additionally introduced iron atoms was investigated by deep level transient spectroscopy. Gettering sets in at a dose of 10 1°cm -2 and is completed for a carbon dose of 10 1h cm -2 for iron doses up to 10 1; cm -2. The microstructure of such a buried layer is characterised by a narrow band of dark contrast containing mainly stacking faults of the extrinsic type .
Physica B: Condensed Matter, 2001
Co-implantation of Al (2 Â 10 18 /cm 3 ) and C (1 Â 10 18 /cm 3 ), Al/C, into 6H-SiC and subsequent annealing up to 16501C were performed. Vacancy-type defects in the implanted layers were studied by positron annihilation spectroscopy. The mean size of vacancy-type defects produced by Al/C-implantation is found to be close to the size of divacancy. The mean size of vacancy-type defects is hardly changed by annealing below 6001C, and vacancy clustering occurs in an annealing temperature range between 6001C and 10001C. At annealing temperatures between 10001C and 14001C, the mean size of vacancy-type defects decreases, and the major vacancy defects are annealed out above 14001C. No significant difference is observed in the annealing behavior of vacancy-type defects between samples implanted with Al/C and only Al. r
In Situ Study of Low-Temperature Irradiation-Induced Defects in Silicon Carbide
Journal of Electronic Materials, 2019
Ni/4H-SiC Schottky barrier diodes have been irradiated by 5.4-MeV helium ions at cryogenic temperatures and their electrical characteristics investigated. Only the prominent native defects (E 0.11 , E 0.16 , and E 0.65) were observed before and after low-temperature irradiation at 50 K, with a baseline on the spectrum observed starting at 190 K. Low-temperature irradiation reduced the concentration of native E 0.11 and E 0.16 defects. After annealing at 380 K, E 0.37 , E 0.58 , E 0.62 , E 0.73 , and E 0.92 defects were observed. These results show that E 0.62 , an acceptor level of the Z 1 center, and E 0.73 , an acceptor level of the Z 2 center, are both secondary defects which are not formed directly from the irradiation process but from succeeding thermal reactions. An interpretation of the formation of the secondary defects is given.
Carbon clustering in Si 1− x C x formed by ion implantation
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1996
Silicon-carbon alloys were formed by multiple energy implantation of C + ions in silicon and in Silicon on Sapphire (SOS). The ion fluence ranged between 5 X 1016 -3 X 10" ions/cm' and the energy between IO-30 keV in order to obtain constant carbon concentration into a depth of 100 nm. The carbon atomic fraction (x) was in the range 0.22-0.59 as tested by Rutherford backscattering spectrometry (RBS). Thermal annealing of the implanted films induced a transition from amorphous to a polycrystalline structure at temperatures above 850°C as detected by Infrared spectrometry (lR) in the wavenumber range 600-900 cm-'. The optical energy gap and the intensity of the infrared signal after annealing at 1000°C depended on the film composition: they both increased linearly with carbon concentration reaching a maximum at the stoichiometric composition (x = 0.5). At higher carbon concentration the lR intensity saturated and the optical energy gap decreased from the maximum value of 2.2 to 1.8 eV. The behaviour at the high carbon content has been related to the formation of graphitic clusters as detected by Raman spectroscopy.
Effects of ion beam irradiation on the crystallization of Si–C films
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1999
Radiation eects of 2 MeV Ar ions on the crystallization of Si±C ®lms were investigated with RHEED and XPS. The carbon ®lms deposited on Si(1 0 0) at 300 K were amorphous. Under ion irradiation, the carbon ®lms thinner than 2 nm reacted with silicon substrates and amorphous SiC ®lms were formed at ambient temperature (<400 K). The SiC ®lms were grown epitaxially by further ion irradiation. The epitaxial relationship between the SiC ®lm and the substrate was (1 0 0) SiC //(1 0 0) Si and [0 0 1] SiC //[0 0 1] Si . The surface of the carbon ®lms thicker than 2 nm was grown to the turbostratic graphite by ion irradiation. The thickness-ion dose dependence of the ®lm structure was presented. Ó 1999 Elsevier Science B.V. All rights reserved. 0168-583X/98/$ ± see front matter Ó 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 -5 8 3 X ( 9 8 ) 0 0 7 4 3 -5
Journal of Applied Physics, 2015
The carbon vacancy (V C) is a prevailing point defect in high-purity 4H-SiC epitaxial layers, and it plays a decisive role in controlling the charge carrier lifetime. One concept of reducing the V C-concentration is based on carbon self-ion implantation in a near surface layer followed by thermal annealing. This leads to injection of carbon interstitials (C i 's) and annihilation of V C 's in the epi-layer "bulk". Here, we show that the excess of C atoms introduced by the self-ion implantation plays a negligible role in the V C annihilation. Actually, employing normalized implantation conditions with respect to displaced C atoms, other heavier ions like Al and Si are found to be more efficient in annihilating V C 's. Concentrations of V C below $2 Â 10 11 cm À3 can be reached already after annealing at 1400 C, as monitored by deep-level transient spectroscopy. This corresponds to a reduction in the V C-concentration by about a factor of 40 relative to the as-grown state of the epilayers studied. The negligible role of the implanted species itself can be understood from simulation results showing that the concentration of displaced C atoms exceeds the concentration of implanted species by two to three orders of magnitude. The higher efficiency for Al and Si ions is attributed to the generation of collision cascades with a sufficiently high energy density to promote C i-clustering and reduce dynamic defect annealing. These C i-related clusters will subsequently dissolve during the post-implant annealing giving rise to enhanced C i injection. However, at annealing temperatures above 1500 C, thermodynamic equilibrium conditions start to apply for the V Cconcentration, which limit the net effect of the C i injection, and a competition between the two processes occurs. V
Precipitates and voids in cubic silicon carbide implanted with 25Mg+ ions
Journal of Nuclear Materials, 2018
Single crystal cubic phase silicon carbide (3C-SiC) films on Si were implanted to 9.6 Â 10 16 25 Mg þ /cm 2 at 673 K and annealed at 1073 and 1573 K for 2, 6, and 12 h in an Ar environment. The data from scanning transmission election microscopy (STEM) and electron energy loss spectroscopy (EELS) mapping suggest a possible formation of unidirectionally aligned tetrahedral precipitates of core (MgC 2)-shell (Mg 2 Si) in the implanted sample annealed at 1573 K for 12 h. There are also small spherical voids near the surface and larger faceted voids around the region of maximum vacancy concentration. Atom probe tomography confirms 25 Mg segregation dominated by small atomic clusters with local 25 Mg concentrations up to 85 at.%. The resulting precipitate size and number density are found to decrease and increase, respectively, probably as a result of the thermal annealing that decomposes the 25 Mg-bearing precipitates at the elevated temperatures and subsequent nucleation and growth below 1073 K during the cooling stage. The results from this study provide data needed to fully understand the property degradation of SiC in a high-flux fast neutron environment.