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

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.

2007 ◽  
Vol 556-557 ◽  
pp. 465-468 ◽  
Author(s):  
Nguyen Tien Son ◽  
Patrick Carlsson ◽  
Björn Magnusson ◽  
Erik Janzén

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.


2008 ◽  
Vol 600-603 ◽  
pp. 381-384 ◽  
Author(s):  
Patrick Carlsson ◽  
Nguyen Tien Son ◽  
Björn Magnusson ◽  
Anne Henry ◽  
Erik Janzén

High-purity, semi-insulating 6H-SiC substrates grown by high-temperature chemical vapor deposition were studied by electron paramagnetic resonance (EPR). The carbon vacancy (VC), the carbon vacancy-antisite pair (VCCSi) and the divacancy (VCVSi) were found to be prominent defects. The (+|0) level of VC in 6H-SiC is estimated by photoexcitation EPR (photo-EPR) to be at ~ 1.47 eV above the valence band. The thermal activation energies as determined from the temperature dependence of the resistivity, Ea~0.6-0.7 eV and ~1.0-1.2 eV, were observed for two sets of samples and were suggested to be related to acceptor levels of VC, VCCSi and VCVSi. The annealing behavior of the intrinsic defects and the stability of the SI properties were studied up to 1600°C.


2006 ◽  
Vol 911 ◽  
Author(s):  
William C Mitchel ◽  
W. D. Mitchell ◽  
H. E. Smith ◽  
W. E. Carlos ◽  
E. R. Glaser

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.


2006 ◽  
Vol 911 ◽  
Author(s):  
Nguyen Tien Son ◽  
Patrick Carlsson ◽  
Björn Magnusson ◽  
Erik Janzén

AbstractElectron paramagnetic resonance was used to study defects in high-purity semi-insulating (HPSI) substrates grown by high-temperature chemical vapor deposition and physical vapor transport. Deep level defects associated to different thermal activation energies of the resistivity ranging from ~0.6 eV to ~1.6 eV in HPSI substrates are identified and their roles in carrier compensation processes are discussed. Based on the results obtained in HPSI materials, we discuss the carrier compensation processes in vanadium-doped SI SiC substrates and different activation energies in the material.


1985 ◽  
Vol 46 ◽  
Author(s):  
N. D. Wilsey ◽  
T. A. Kennedy

AbstractThe use of electron paramagnetic resonance to investigate intrinsic defects in the III-V semiconductors is reviewed. Particular attention is given to lattice vacancies, antisites and their complexes in GaP, GaAs, and InP. The role of EPR in arriving at an understanding of these defects is emphasized and the interplay between experiment and theory is discussed.


1989 ◽  
Vol 163 ◽  
Author(s):  
Masashi Suezawa ◽  
Koji Sumino

AbstractThe generation and dissociation processes of Fe-B pairs in Si crystal are investigated by means of the measurements of electron paramagnetic resonance of Si crystals of various B concentrations doped with Fe. Fe-B pairs are generated due to annealing of the crystals at temperatures around 300 K obeying to the first order reaction kinetics. The activation energy for pair generation is determined to be about 0.65 eV which is almost equal to the migration energy of Fe impurity in a Si crystal. Fe-B pairs are found to be dissociated at tempeatures higher than 150°C leading to the precipitation of Fe.


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