Annealing behavior between room temperature and 2000°C of deep level defects in electron-irradiated n -type 4H silicon carbide J. Appl. Phys. 98, 043518 (2005); 10.1063/1.2009816 Deep levels created by low energy electron irradiation in 4 H -SiC A deep level transient spectroscopy study of electron irradiation induced deep levels in p-type 6H-SiCDeep level defects in electron-irradiated 4H SiC epitaxial layers grown by chemical vapor deposition were studied using deep level transient spectroscopy. The measurements performed on electron-irradiated p ϩ n junctions in the temperature range 100-750 K revealed several electron traps and one hole trap with thermal ionization energies ranging from 0.35 to 1.65 eV. Most of these defects were already observed at a dose of irradiation as low as Ϸ 5ϫ10 13 cm Ϫ2 . Dose dependence and annealing behavior of the defects were investigated. For two of these electron traps, the electron capture cross section was measured. From the temperature dependence studies, the capture cross section of these two defects are shown to be temperature independent.

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Electrically active defects in irradiated 4H-SiC J. Appl. Phys. 95, 4728 (2004); 10.1063/1.1689731Electron-irradiation-induced deep levels in n-type 6H-SiC A deep level transient spectroscopy study of electron irradiation induced deep levels in p-type 6H-SiCAn investigation of electron irradiation induced deep levels in 6H-SiC p ϩ n diodes grown by chemical vapor deposition has been performed. Deep level transient spectroscopy ͑DLTS͒ reveals several overlapping peaks in the temperature range 140-650 K. The electron capture cross sections have been measured by directly observing the variation of the DLTS peak height with the duration of the filling pulse and fitting the capacitance transient using multiple linear regression. Temperature dependence studies of the electron capture cross section were performed on three of the observed levels.

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Detailed information about the electronic structure of the lowest-lying excited states and the ground state of the neutral silicon vacancy in 4H and 6H SiC has been obtained by high-resolution photoluminescence ͑PL͒, PL excitation ͑PLE͒, and Zeeman spectroscopy of both PL and PLE. The excited states and the ground states involved in the characteristic luminescence of the defect with no-phonon ͑NP͒ lines at 1.438 and 1.352 eV in 4H SiC and 1.433, 1.398, and 1.368 eV in 6H SiC are shown to be singlets. The orbital degeneracy of the excited states is lifted by the crystal field for the highest-lying NP lines corresponding to one of the inequivalent lattice sites in both polytypes, leading to the appearance of hot lines at slightly higher energies. Polarization studies of the NP lines show a different behavior for the inequivalent sites. A comparison of this behavior in the two polytypes together with parameters from spin resonance studies provides useful hints for the assignment of the no-phonon lines to the inequivalent sites. In strained samples an additional fine structure of the NP lines can be resolved. This splitting may be due to strain variations in the samples.