Defect energy levels in electron-irradiated and deuterium-implanted6Hsilicon carbide

Abstract

Using deep-level transient spectroscopy, we studied defect energy levels and their annealing behavior in nitrogen-doped $6H\ensuremath{-}\mathrm{SiC}$ epitaxial layers irradiated with 2-MeV electrons and implanted with 300-KeV deuterium or hydrogen at room temperature. Five levels located at ${E}_{c}\ensuremath{-}0.34,$ ${E}_{c}\ensuremath{-}0.41,$ ${E}_{c}\ensuremath{-}0.51,$ ${E}_{c}\ensuremath{-}0.62,$ and ${E}_{c}\ensuremath{-}0.64\mathrm{eV}$ consistently appear in various samples grown by chemical vapor deposition, showing they are characteristic defects in n-type $6H\ensuremath{-}\mathrm{SiC}$ epitaxial layers. It is suggested that the ${E}_{c}\ensuremath{-}0.51\mathrm{eV}$ level originates from a carbon vacancy, and that the two levels at ${E}_{c}\ensuremath{-}0.34$ and ${E}_{c}\ensuremath{-}0.41\mathrm{eV},$ which likely arise from the occupation of inequivalent lattice sites, and the level at ${E}_{c}\ensuremath{-}0.51\mathrm{eV}$ are different charge states of the carbon vacancy. The annealing kinetics of the ${E}_{c}\ensuremath{-}0.51\mathrm{eV}$ level are first order with an activation energy of 1.45 eV, and a level at ${E}_{c}\ensuremath{-}0.87\mathrm{eV}$ growing upon its decay arises most likely from a vacancy-impurity complex. The results for the ${E}_{c}\ensuremath{-}0.62\mathrm{eV}$ and ${E}_{c}\ensuremath{-}0.64\mathrm{eV}$ 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 ${10}^{11}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ no interaction between hydrogen and the irradiation-induced silicon vacancy takes place even after annealing at temperatures up to 800 \ifmmode^\circ\else\textdegree\fi{}C, in contrast to the results reported for n-type silicon.