Defect energy levels in electron-irradiated and deuterium-implanted 6 H silicon carbide

Using deep-level transient spectroscopy, we studied defect energy levels and their annealing behavior in nitrogen-doped 6H-SiC epitaxial layers irradiated with 2-MeV electrons and implanted with 300-KeV deuterium or hydrogen at room temperature. Five levels located at Ec-0.34, Ec-0.41, Ec-0.51, Ec-0.62, and Ec-0.64eV consistently appear in various samples grown by chemical vapor deposition, showing they are characteristic defects in n-type 6H-SiC epitaxial layers. It is suggested that the Ec-0.51eV level originates from a carbon vacancy, and that the two levels at Ec-0.34 and Ec-0.41eV, which likely arise from the occupation of inequivalent lattice sites, and the level at Ec-0.51eV are different charge states of the carbon vacancy. The annealing kinetics of the Ec-0.51eV level are first order with an activation energy of 1.45 eV, and a level at Ec-0.87eV growing upon its decay arises most likely from a vacancy-impurity complex. The results for the Ec-0.62eV and Ec-0.64eV levels are consistent with a defect model involving a silicon vacancy on inequivalent sites in the $6H$ lattice. Furthermore, the present results show that at hydrogen doses of 10¹¹cm^-2 no interaction between hydrogen and the irradiation-induced silicon vacancy takes place even after annealing at temperatures up to 800 ^∘{}C, in contrast to the results reported for n-type silicon.