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 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.

A study of V3+ and the Vanadium acceptor level in semi-insulating 6H-SiC

2005 ◽  
Vol 864 ◽  
Author(s):  
Wonwoo Lee ◽  
Mary E. Zvanut
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Charge State ◽  
Thermal Relaxation ◽  
Conduction Band Edge ◽  
Ir Absorption ◽  
Acceptor Level ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
The Difference ◽  
Electron Paramagnetic

AbstractInfrared absorption (IR) and electron paramagnetic resonance (EPR) spectroscopies are used to study the V3+ impurity and the vanadium acceptor level in 6H semi-insulating SiC. IR and EPR data obtained from samples cut from the same wafer support the assignment of the 0.60 and 0.62 eV IR absorption lines to substitutional V3+. Photo-induced EPR measurements reveal identical photo-thresholds for V3+ and V4+ ions. A peak at 0.8 eV, where the intensity of the three plus charge state decreases and the four plus charge state increases by an equal amount, is thought to represent excitation of an electron from V3+ to the conduction band edge. The 0.8 eV peak is therefore attributed to the V3+/4+ level. The difference between the optically measured value reported here and that measured previously using temperature dependent techniques is attributed thermal relaxation.

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.

Electron Paramagnetic Resonance Studies of Intrinsic Bonding Defects and Impurities in SiO2 Thin Solid Films

1985 ◽  
Vol 61 ◽  
Author(s):  
Robert N. Schwartz ◽  
Marion D. Clark ◽  
Walee Chamulitrat ◽  
Larry Kevan
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Rf Sputtering ◽  
Chemical Vapor ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Pressure Chemical ◽  
Defects And Impurities ◽  
Electron Paramagnetic

ABSTRACTElectron paramagnetic resonance (EPR) spectroscopy has been used to identify paramagnetic intrinsic bonding defects and impurities in as-deposited thin solid SiO2 films. Thin films grown by E-beam vacuum deposition, RF sputtering, thermal oxidation of polysilicon, plasma enhanced chemical vapor deposition (PECVD), and low pressure chemical vapor deposition (LPCVD) techniques have been examined. Some of the growth techniques yield films that have paramagnetic centers similar to those found in bulk radiation-damaged vitreous SiO2. A new temperature dependent EPR center was observed in PECVD SiO2 films and has been assigned to trapped NO2. Slow-motional EPR lineshape theory was used to analyze the temperature dependent spectra.

Electrical Properties of Undoped 6H- and 4H-SiC Bulk Crystals Grown by Halide Chemical Vapor Deposition

2006 ◽  
Vol 527-529 ◽  
pp. 625-628
Author(s):  
Hun Jae Chung ◽  
Sung Wook Huh ◽  
A.Y. Polyakov ◽  
Saurav Nigam ◽  
Qiang Li ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Boron Concentration ◽  
Secondary Ion Mass Spectrometry ◽  
Nitrogen Concentration ◽  
Chemical Vapor ◽  
Bulk Crystals ◽  
Hall Effect Measurements ◽  
Site Competition ◽  
Secondary Ion

Undoped 6H- and 4H-SiC crystals were grown by Halide Chemical Vapor Deposition (HCVD). Concentrations of impurities were measured by various methods including secondary-ion-mass spectrometry (SIMS). With increasing C/Si ratio, nitrogen concentration decreased and boron concentration increased as expected for the site-competition effect. Hall-effect measurements on 6H-SiC crystals showed that with the increase of C/Si ratio from 0.06 to 0.7, the Fermi level was shifted from Ec-0.14 eV (nitrogen donors) to Ev+0.6 eV (B-related deep centers). Crystals grown with C/Si > 0.36 showed high resistivities between 1053 and 1010 4cm at room temperature. The high resistivities are attributed to close values of the nitrogen and boron concentrations and compensation by deep defects present in low densities.

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