Deep Levels and Compensation in High Purity Semi-Insulating 4H-SiC

2006 ◽  
Vol 911 ◽  
Author(s):  
William C Mitchel ◽  
W. D. Mitchell ◽  
H. E. Smith ◽  
W. E. Carlos ◽  
E. R. Glaser
Keyword(s):  
High Purity ◽  
Secondary Ion Mass Spectrometry ◽  
Activation Energies ◽  
Deep Levels ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Carbon Vacancy ◽  
Near Ir ◽  
Electron Paramagnetic ◽  
Secondary Ion

AbstractA study of temperature dependent Hall effect (TDH), electron paramagnetic resonance (EPR), photoluminescence (PL) and secondary ion mass spectrometry (SIMS) measurements has been made on high purity semi-insulating (HPSI) 4H-SiC crystals grown by the physical vapor transport technique. Thermal activation energies from TDH varied from a low of 0.55 eV to a high of 1.5 eV. All samples studied showed n-type conduction with the Fermi level in the upper half of the band gap. Carrier concentration measurements indicated the deep levels had to be present in concentrations in the low 1015 cm-3 range. Several defects were detected by EPR including the carbon vacancy and the carbon-silicon divacancy. PL measurements in the near IR showed the presence of the UD-1, UD-2 and UD-3 emission lines that have been found in HPSI material. No correlation between the relative intensities of the PL lines and the TDH activation energies was seen. SIMS measurements on nitrogen, boron and other common impurities indicate nitrogen and boron concentrations higher than those of individual deep levels as determined by TDH or of intrinsic defects as determined by EPR such as the carbon vacancy or the divacancy. It is determined that several different defects with concentrations greater than or equal to 1x1015 cm-3 are required to compensate the residual nitrogen and boron.

Intrinsic Defects in Semi-Insulating SiC: Deep Levels and their Roles in Carrier Compensation

2007 ◽  
Vol 556-557 ◽  
pp. 465-468 ◽  
Author(s):  
Nguyen Tien Son ◽  
Patrick Carlsson ◽  
Björn Magnusson ◽  
Erik Janzén
Keyword(s):  
Electron Paramagnetic Resonance ◽  
High Purity ◽  
Thermal Activation ◽  
Activation Energies ◽  
Deep Levels ◽  
Paramagnetic Resonance ◽  
Intrinsic Defects ◽  
Carbon Vacancy ◽  
Reported Data ◽  
Electron Paramagnetic

Vacancies, divacancies and carbon vacancy-carbon antisite pairs are found by electron paramagnetic resonance (EPR) to be dominant defects in high-purity semi-insulating (HPSI) 4HSiC substrates having different thermal activation energies of the resistivity ranging from ~0.8 eV to ~1.6 eV. Based on EPR results and previously reported data, the energy positions of several acceptor states of the vacancies and vacancy-related complexes are estimated. These deep levels are suggested to be associated to different thermal activation energies and responsible for the semiinsulating behaviour in HPSI SiC substrates. Their role in carrier compensation is discussed.

Electrical Measurement of the Vanadium Acceptor Level in 4H- and 6H-SiC

2006 ◽  
Vol 911 ◽  
Author(s):  
William C Mitchel ◽  
William D. Mitchell ◽  
H. E. Smith ◽  
M. E. Zvanut ◽  
Wonwoo Lee
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Nitrogen Concentration ◽  
Local Strain ◽  
Electrical Measurement ◽  
Acceptor Level ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Ionization Energies ◽  
Electron Paramagnetic ◽  
Secondary Ion

AbstractTemperature dependent Hall effect, Fourier transform infrared absorption, and electron paramagnetic resonance (EPR) studies have been performed on both 6H and 4H vanadium doped semi-insulating SiC samples grown by the physical vapor transport technique. Nitrogen and boron concentrations have been measured in some samples by secondary ion mass spectrometry (SIMS). Unlike undoped s.i. SiC, where several different thermal ionization energies have been observed, the ionization energies for all of the vanadium doped s.i. samples studied here were found to cluster around only two values for the two polytypes, EC – 0.85 eV and EC – 1.54 eV for 6H and EC – 1.11 eV and EC – 1.57 eV for 4H. SIMS measurements indicate that the nitrogen concentration exceeds the boron concentration in samples with the shallower of two values while the opposite is true for the deeper level samples. EPR detected both V3+ and V4+ in shallower level samples while only V4+ was detected in the deeper level samples. These results indicate that the vanadium acceptor level, V3+/4+, is located at EC – 0.85 eV in 6H-SiC and EC – 1.11 eV in 4H-SiC. However, some EPR results do show a small, unexpected asymmetry in the angular dependence of the V4+ signal, most noticeably in the 4H samples. This suggests that at least some of the vanadium related levels might be complexed with another defect or be under higher local strain than expected.

Deep Levels Responsible for Semi-Insulating Behavior in Vanadium-Doped 4H-SiC Substrates

2008 ◽  
Vol 600-603 ◽  
pp. 401-404
Author(s):  
Nguyen Tien Son ◽  
Patrick Carlsson ◽  
Andreas Gällström ◽  
Björn Magnusson ◽  
Erik Janzén
Keyword(s):  
Activation Energy ◽  
Electron Paramagnetic Resonance ◽  
Thermal Activation ◽  
Activation Energies ◽  
Thermal Activation Energy ◽  
Deep Levels ◽  
Paramagnetic Resonance ◽  
Intrinsic Defects ◽  
Carbon Vacancy ◽  
Electron Paramagnetic

Semi-insulating (SI) 4H-SiC substrates doped with vanadium (V) in the range 5.5×1015 –1.1×1017 cm–3 were studied by electron paramagnetic resonance. We show that only in heavily V-doped 4H-SiC vanadium is responsible for the SI behavior, whereas in moderate V-doped substrates with the V concentration comparable or slightly higher than that of the shallow N donor or B acceptor, the SI properties are thermally unstable and determined by intrinsic defects. The results show that the commonly observed thermal activation energy Ea~1.1 eV in V-doped 4H-SiC, which was previously assigned to the single acceptor V4+/3+ level, may be related to deep levels of the carbon vacancy. Carrier compensation processes involving deep levels of V and intrinsic defects are discussed and possible thermal activation energies are suggested.

scholarly journals The Carbon Vacancy Related EI4 Defect in 4H-SiC

2010 ◽  
Vol 645-648 ◽  
pp. 399-402 ◽  
Author(s):  
Nguyen Tien Son ◽  
Patrick Carlsson ◽  
Junichi Isoya ◽  
Norio Morishita ◽  
Takeshi Ohshima ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
High Purity ◽  
Room Temperature ◽  
Paramagnetic Resonance ◽  
Annealing Behaviour ◽  
Carbon Vacancy ◽  
Epr Signal ◽  
Electron Paramagnetic

Electron paramagnetic resonance (EPR) was used to study high-purity semi-insulating 4H-SiC irradiated with 2 MeV electrons at room temperature. The EPR signal of the EI4 defect was found to be dominating in samples irradiated and annealed at ~750°C. Additional large-splitting 29Si hyperfine (hf) lines and also other 13C and 29Si hf structures were observed. Based on the observed hf structures and annealing behaviour, the complex between a negative carbon vacancy-carbon antisite pair (VCCSi–) and a distance positive carbon vacancy ( ) is tentatively proposed as a possible model for the EI4 defect.

Deep Level Point Defects in Semi-Insulating SiC

2006 ◽  
Vol 527-529 ◽  
pp. 517-522 ◽  
Author(s):  
Mary Ellen Zvanut ◽  
Won Woo Lee ◽  
Hai Yan Wang ◽  
W.C. Mitchel ◽  
William D. Mitchell
Keyword(s):  
Point Defects ◽  
Deep Level ◽  
High Resistivity ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Carbon Vacancy ◽  
Device Applications ◽  
Electron Paramagnetic ◽  
Epr Experiments ◽  
Positively Charged

The high resistivity of SiC required for many device applications is achieved by compensating residual donors or acceptors with vanadium or intrinsic defects. This work addresses the defect levels of substitutional vanadium and the positively charged carbon vacancy (VC +) in semiinsulating (SI) SiC. After reviewing the earlier studies related to both defects, the paper focuses on temperature-dependent Hall measurements and photo-induced electron paramagnetic resonance (EPR) experiments of 4H and 6H SI SiC. In vanadium-doped samples, a V3+/4+ level near Ec-1.1 eV (4H) and Ec-0.85 eV (6H) is estimated by a comparison of dark EPR spectra and the activation energy determined from the Hall data, assuming that vanadium controls the Fermi level. In high purity semiinsulating substrates, analysis of time-dependent and steady-state photo-EPR data suggests that the plus-to-neutral transition of the carbon vacancy involves a structural relaxation of about 0.6 eV.

Temperature Dependent Line-Shape of the Silicon Dangling Bond EPR-Resonance in Polycrystalline Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
N. H. Nickel ◽  
E. A. Schiff
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Polycrystalline Silicon ◽  
Room Temperature ◽  
Dangling Bond ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Temperature Electron ◽  
Motional Narrowing ◽  
G Value ◽  
Electron Paramagnetic

AbstractThe temperature dependence of the silicon dangling-bond resonance in polycrystalline (poly-Si) and amorphous silicon (a-Si:H) was measured. At room temperature, electron paramagnetic resonance (EPR) measurements reveal an isotropie g-value of 2.0055 and a line width of 6.5 and 6.1 G for Si dangling-bonds in a-Si:H and poly-Si, respectively. In both materials spin density and g-value are independent of temperature. While in a-Si:H the width of the resonance did not change with temperature, poly-Si exhibits a remarkable T dependence of ΔHpp. In unpassivated poly-Si a pronounced decrease of ΔHpp is observed for temperatures above 300 K. At 384 K ΔHpp reaches a minimum of 5.1 G, then increases to 6.1 G at 460 K, and eventually decreases to 4.6 G at 530 K. In hydrogenated poly-Si ΔHpp decreases monotonically above 425 K. The decrease of ΔHpp is attributed to electron hopping causing motional narrowing. An average hopping distance of 15 and 17.5 Å was estimated for unhydrogenated and H passivated poly-Si, respectively.

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