Microscopic Structure and Electrical Activity of 4H-SiC/SiO_2 Interface Defects : an EPR study of oxidized porous SiC

摘要

The oxidation related defects in porous n-type 4H-SiC have been studied by electron paramagnetic resonance spectroscopy. Two main centers are observed after a 1000℃ oxidation in dry oxygen. The first one is isotropic with a g-factor of 2.0028 ; it is attributed to a carbon related center in the oxide. The second center is anisotropic with C3V or Cn, symmetries depending on its orientation relative to the c-axis. Its g-factors are g/_(/c)=2.0024 and g_(⊥c)=2.00315 and g_(xx)=2.0031, g_(yy)=2.0028, g_(zz)=2.0023. From its central and ligand hyperfine interactions it is attributed to a Pb like carbon dangling bond center at the SiC side of the interface:(P_(bC)). The P_(bc) is electrically active and introduces a deep level. The concentrations of the two defects are estimated to [C]=10~(18)cm~(-3) and [P_(bc)]=10~(l2)cm~(-2).