Structural defects and deep-level centers in 4H-SiC epilayers grown by sublimational epitaxy in vacuum

The parameters of deep-level centers in lightly doped 4H-SiC epilayers grown by sublimational epitaxy and CVD were investigated. Two deep-level centers with activation energies E _c -0.18 eV and E _c -0.65 eV (Z1 center) were observed and tentatively identified with structural defects of the SiC crystal lattice. The Z1 center concentration is shown to fall with decreasing uncompensated donor concentration N _d -N _a in the layers. For the same N _d -N _a , the Z1 center concentration is lower in layers with a higher dislocation density.