Acceptor levels of the carbon vacancy in 4<i>H</i>-SiC: Combining Laplace deep level transient spectroscopy with density functional modeling

Capan, Ivana; Brodar, Tomislav; Coutinho, J.; Ohshima, Takeshi; Markevich, V. P.; Peaker, А. R.

doi:10.1063/1.5063773

Cited by 26 publications

(54 citation statements)

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“…The Z 1/2 is a well-known deep level and previously assigned to a transition between double negative and neutral charge state of carbon vacancy V C (=/0) [52]. As recently reported [23,24], two emission lines Z 1 (=/0) and Z 2 (=/0) are resolved by the Laplace DLTS technique and assigned to carbon vacancies residing on two different lattice sites with local cubic and hexagonal symmetry. DLTS spectra of as-grown, ion implanted, and neutron irradiated 4H-SiC SBDs are shown in Figure 3.…”

Section: Depth Profiling Of Eh1 and Eh3 Deep Level Defectsmentioning

confidence: 65%

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Depth Profile Analysis of Deep Level Defects in 4H-SiC Introduced by Radiation

et al. 2020

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Deep level defects created by implantation of light-helium and medium heavy carbon ions in the single ion regime and neutron irradiation in n-type 4H-SiC are characterized by the DLTS technique. Two deep levels with energies 0.4 eV (EH1) and 0.7 eV (EH3) below the conduction band minimum are created in either ion implanted and neutron irradiated material beside carbon vacancies (Z1/2). In our study, we analyze components of EH1 and EH3 deep levels based on their concentration depth profiles, in addition to (−3/=) and (=/−) transition levels of silicon vacancy. A higher EH3 deep level concentration compared to the EH1 deep level concentration and a slight shift of the EH3 concentration depth profile to larger depths indicate that an additional deep level contributes to the DLTS signal of the EH3 deep level, most probably the defect complex involving interstitials. We report on the introduction of metastable M-center by light/medium heavy ion implantation and neutron irradiation, previously reported in cases of proton and electron irradiation. Contribution of M-center to the EH1 concentration profile is presented.

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Section: Depth Profiling Of Eh1 and Eh3 Deep Level Defectsmentioning

confidence: 65%

“…Acceptor levels of the carbon vacancy exhibit negative-U ordering [22]. Two components of the Z 1/2 center were recently resolved by Laplace deep level transient spectroscopy (Laplace DLTS) and assigned to the (=/0) acceptor level of carbon vacancies residing on lattice sites with local cubic and hexagonal symmetry [23,24].…”

Section: Introductionmentioning

confidence: 99%

Depth Profile Analysis of Deep Level Defects in 4H-SiC Introduced by Radiation

et al. 2020

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“…The Z 1/2 is a well-known deep level and previously assigned to a transition between double negative and neutral charge state of carbon vacancy V C (=/0) [26]. As recently reported [27,28], two emission lines, Z 1 (=/0) and Z 2 (=/0), are resolved by the Laplace DLTS technique and assigned to carbon vacancies residing on two different lattice sites with local cubic and hexagonal symmetry. Carbon vacancy is acting as a strong recombination center and is thus the main life-time limiting defect in as-grown 4H-SiC, which is one of the crucial properties for radiation detectors and electronic devices in general [29].…”

Section: Electrical Characterization Of Sic Detectorsmentioning

confidence: 68%

Response of 4H-SiC Detectors to Ionizing Particles

et al. 2020

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We report the response of newly designed 4H-SiC Schottky barrier diode (SBD) detector prototype to alpha and gamma radiation. We studied detectors of three different active area sizes (1 × 1, 2 × 2 and 3 × 3 mm2), while all detectors had the same 4H-SiC epi-layer thickness of approximately µm, sufficient to stop alpha particles up to 6.8 MeV, which have been used in this study. The detector response to the various alpha emitters in the 3.27 MeV to 8.79 MeV energy range clearly demonstrates the excellent linear response to alpha emissions of the detectors with the increasing active area. The detector response in gamma radiation field of Co-60 and Cs-137 sources showed a linear response to air kerma and to different air kerma rates as well, up to 4.49 Gy/h. The detector response is not in saturation for the dose rates lower than 15.3 mGy/min and that its measuring range for gamma radiation with energies of 662 keV, 1.17 MeV and 1.33 MeV is from 0.5 mGy/h–917 mGy/h. No changes to electrical properties of pristine and tested 4H-SiC SBD detectors, supported by a negligible change in carbon vacancy defect density and no creation of other deep levels, demonstrates the radiation hardness of these 4H-SiC detectors.

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“…The latter defect is associated with the V C and corresponds to a twofold electron emission due to a (−2/0) transition [15]. Vacancies at hexagonal and pseudocubic lattice sites have similar energy level positions and are only distinguishable by Laplace-DLTS [62]. The S 1 and S 2 centers arise in implanted samples but are less stable than the Z 1/2 level, and disappear at high temperatures [61] as seen in Fig.…”

Section: B Experimentsmentioning

confidence: 95%

Anisotropic and plane-selective migration of the carbon vacancy in SiC: Theory and experiment

et al. 2019

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We investigate the migration mechanism of the carbon vacancy (V C) in silicon carbide (SiC) using a combination of theoretical and experimental methodologies. The V C , commonly present even in state-of-the-art epitaxial SiC material, is known to be a carrier lifetime killer and therefore strongly detrimental to device performance. The desire for V C removal has prompted extensive investigations involving its stability and reactivity. Despite suggestions from theory that V C migrates exclusively on the C sublattice via vacancy-atom exchange, experimental support for such a picture is still unavailable. Moreover, the existence of two inequivalent locations for the vacancy in 4H-SiC [hexagonal, V C (h), and pseudocubic, V C (k)] and their consequences for V C migration have not been considered so far. The first part of the paper presents a theoretical study of V C migration in 3C-and 4H-SiC. We employ a combination of nudged elastic band (NEB) and dimer methods to identify the migration mechanisms, transition state geometries, and respective energy barriers for V C migration. In 3C-SiC, V C is found to migrate with an activation energy of E A = 4.0 eV. In 4H-SiC, on the other hand, we anticipate that V C migration is both anisotropic and basal-plane selective. The consequence of these effects is a slower diffusivity along the axial direction, with a predicted activation energy of E A = 4.2 eV, and a striking preference for basal migration within the h plane with a barrier of E A = 3.7 eV, to the detriment of the k-basal plane. Both effects are rationalized in terms of coordination and bond angle changes near the transition state. In the second part, we provide experimental data that corroborates the above theoretical picture. Anisotropic migration of V C in 4H-SiC is demonstrated by deep level transient spectroscopy (DLTS) depth profiling of the Z 1/2 electron trap in annealed samples that were subject to ion implantation. Activation energies of E A = (4.4 ± 0.3) eV and E A = (3.6 ± 0.3) eV were found for V C migration along the c and a directions, respectively, in excellent agreement with the analogous theoretical values. The corresponding prefactors of D 0 = 0.54 cm 2 /s and 0.017 cm 2 /s are in line with a simple jump process, as expected for a primary vacancy point defect.

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Acceptor levels of the carbon vacancy in 4H-SiC: Combining Laplace deep level transient spectroscopy with density functional modeling

Cited by 26 publications

References 50 publications

Depth Profile Analysis of Deep Level Defects in 4H-SiC Introduced by Radiation

Depth Profile Analysis of Deep Level Defects in 4H-SiC Introduced by Radiation

Response of 4H-SiC Detectors to Ionizing Particles

Anisotropic and plane-selective migration of the carbon vacancy in SiC: Theory and experiment

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