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

Using deep-level transient spectroscopy, we studied defect energy levels an d their annealing behavior in nitrogen-doped 6H-SiC epitaxial layers irradi ated with 2-MeV electrons and implanted with 300-KeV deuterium or hydrogen at room temperature. Five levels located at E-c-0.34, E-c-0.41, E-c-0.51, E -c-0.62, and E-c-0.64 eV consistently appear in various samples grown by ch emical vapor deposition, showing they are characteristic defects in n-type 6H-SiC epitaxial layers. It is suggested that the E-c-0.51 eV level origina tes from a carbon vacancy, and that the two levels at E-c-0.34 and E-c-0.41 eV, which likely arise from the occupation of inequivalent lattice sites, a nd the level at E-c-0.51 eV are different charge states of the carbon vacan cy. The annealing kinetics of the E-c-0.51 eV level are first order with an activation energy of 1.45 eV, and a level at E-c-0.87 eV growing upon its decay arises most likely from a vacancy-impurity complex. The results for t he E-c-0.62 eV and E-c-0.64 eV levels are consistent with a defect model in volving a silicon vacancy on inequivalent sites in the 6H lattice. Furtherm ore, the present results show that at hydrogen doses of 10(11) cm(-2) no in teraction between hydrogen and the irradiation-induced silicon vacancy take s place even after annealing at temperatures up to 800 degrees C, in contra st to the results reported for n-type silicon. [S0163-1829(99)13815-3].