Infrared spectra and electron spin resonance of vanadium deep level impurities in silicon carbide

Schneider, J.; Müller, H.; Maier, K.; Wilkening, W.; Fuchs, F.; Dörnen, A.; Leibenzeder, S.; Stein, R.

doi:10.1063/1.102555

Cited by 151 publications

(78 citation statements)

References 3 publications

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“…11,12 The only other identifiable lines are those due to very low concentrations of vanadium in sample A at 0.8947 and 0.9478 eV. 13 The intensities of the vanadium lines are very weak compared to what is seen in intentionally doped material and are close to the SIMS detection limit. We note that the absence of vanadium PL is very rare in PVT grown SiC.…”

Section: Resultsmentioning

confidence: 99%

Electrical properties of unintentionally doped semi-insulating and conducting 6H-SiC

Mitchel¹,

Mitchell²,

Fang³

et al. 2006

Journal of Applied Physics

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Temperature dependent Hall effect ͑TDH͒, low temperature photoluminescence ͑LTPL͒, secondary ion mass spectrometry ͑SIMS͒, optical admittance spectroscopy ͑OAS͒, and thermally stimulated current ͑TSC͒ measurements have been made on 6H-SiC grown by the physical vapor transport technique without intentional doping. n-and p-type as well semi-insulating samples were studied to explore the compensation mechanism in semi-insulating high purity SiC. Nitrogen and boron were found from TDH and SIMS measurements to be the dominant impurities that must be compensated to produce semi-insulating properties. The electrical activation energy of the semi-insulating sample determined from the dependence of the resistivity was 1.0 eV. LTPL lines near 1.00 and 1.34 eV, identified with the defects designated as UD-1 and UD-3, were observed in all three samples but the intensity of the UD-1 line was almost a factor of 10 more in the n-type sample than in the the p-type sample with that in the semi-insulating sample being intermediate between those two. OAS and TSC experiments confirmed the high purity of this material. The results suggest that the relative concentrations of a dominant deep level and nitrogen and boron impurities can explain the electrical properties in this material.

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Section: Resultsmentioning

confidence: 99%

Electrical properties of unintentionally doped semi-insulating and conducting 6H-SiC

Mitchel¹,

Mitchell²,

Fang³

et al. 2006

Journal of Applied Physics

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“…The motivation for this comparison is that the nonempirical optimally tuned hybrids can reproduce excitation energies and quasiparticle spectra [27,28] and furthermore we could successfully correlate the KS eigenvalues of HSE06 + V w calculation with quasiparticle energies [53]. According to Magnusson et al [81,82], the ground state of the defect is located 2.1 ± 0.1 eV below the conduction band edge and there is an interimpurity transition (e → e) with 0.97 eV energy in The more careful treatment of the charge correction compared to our previous study reduces the refined w parameter value with 0.5 eV. Therefore, the calculated positive neutral charge transition level (+|0) is slightly shifted downward with 0.06 eV.…”

Section: V Si In 4h-sicmentioning

confidence: 99%

Theoretical unification of hybrid-DFT andDFT + Umethods for the treatment of localized orbitals

et al. 2014

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Hybrid functionals serve as a powerful practical tool in different fields of computational physics and quantum chemistry. On the other hand, their applicability for the case of correlated d and f orbitals is still questionable and needs more considerations. In this article we formulate the on-site occupation dependent exchange correlation energy and effective potential of hybrid functionals for localized states and connect them to the on-site correction term of the DFT + U method. The resultant formula indicates that the screening of the onsite electron repulsion is governed by the ratio of the exact exchange in hybrid functionals. Our derivation provides a theoretical justification for adding a DFT + U -like on-site potential in hybrid-DFT calculations to resolve issues caused by overscreening of localized states. The resulting scheme, hybrid DFT + V w , is tested for chromium impurity in wurtzite AlN and vanadium impurity in 4H-SiC, which are paradigm examples of systems with different degrees of localization between host and impurity orbitals.

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“…In the 4H and 6H hexagonal polytypes, 3d TMs such as Ti, [14][15][16] V, [17][18][19] Cr, [19][20][21] Sc, 22 and Ni 23 are also known to substitute for Si site and the TM centers at different inequivalent-lattice sites in 4H-and 6H-SiC have been identified. However, there is unclear or no corresponding correlation found for 4d TM impurities such as Mo and Baur and co-workers 24 ), has also been observed for a single lattice site in n-type 6H-and 15R-SiC.…”

Section: Nbmentioning

confidence: 99%

Electron paramagnetic resonance and theoretical studies of Nb in 4H- and 6H-SiC

Són¹,

Trinh²,

Gällström³

et al. 2012

Journal of Applied Physics

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High purity silicon carbide (SiC) materials are of interest from high-power high temperature applications across recent photo-voltaic cells to hosting solid state quantum bits, where the tight control of electrically, optically, and magnetically active point defects is pivotal in these areas. 4H-and 6H-SiC substrates are grown at high temperatures and the incorporation of transition metal impurities is common. In unintentionally Nb-doped 4H-and 6H-SiC substrates grown by high-temperature chemical vapor deposition, an electron paramagnetic resonance (EPR) spectrum with C 1h symmetry and a clear hyperfine (hf) structure consisting of ten equal intensity hf lines was observed. The hf structure can be identified as due to the interaction between the electron spin S ¼ 1/2 and the nuclear spin of 93 Nb. Additional hf structures due to the interaction with three Si neighbors were also detected. In 4H-SiC, a considerable spin density of $37.4% was found on three Si neighbors, suggesting the defect to be a complex between Nb and a nearby carbon vacancy (V C ). Calculations of the , support previous reported results that Nb preferentially forms an asymmetric split-vacancy (ASV) defect. In both 4H-and 6H-SiC, only one Nb-related EPR spectrum has been observed, supporting the prediction from calculations that the hexagonal-hexagonal defect configuration of the ASV complex is more stable than others. V C 2012 American Institute of Physics. [http://dx

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Infrared spectra and electron spin resonance of vanadium deep level impurities in silicon carbide

Cited by 151 publications

References 3 publications

Electrical properties of unintentionally doped semi-insulating and conducting 6H-SiC

Electrical properties of unintentionally doped semi-insulating and conducting 6H-SiC

Theoretical unification of hybrid-DFT andDFT + Umethods for the treatment of localized orbitals

Electron paramagnetic resonance and theoretical studies of Nb in 4H- and 6H-SiC

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