Two defect levels for the carbon vacancy carbon antisite pair in 4H-SIC.

Due to its possible applications in high power devices, 4H-SiC is a material of keen interest to many researchers. The specific structure of point defects is often studied using electron paramagnetic resonance (EPR) while photo EPR allows for the understanding of their defect level. We are using EPR to look at SI5, a carbon-vacancy-carbon-antisite pair, V$_{C}$C$_{Si.}$ The samples were prepared by halide chemical vapor deposition using gasses with different C/Si ratios. The process produces samples with resistivity activation energy, E$_{a}$, between 0.25 eV and 0.85 eV.The photo EPR was performed at 80 K using a quartz tungsten halogen lamp and a monochrometer. Wavelengths were varied between 388 nm and 2400 nm. Results reveal that SI5 has photo-threshold energy of 0.75 eV for samples with E$_{a }$= 0.25 eV and 0.5 eV while samples with E$_{a}$ of 0.85 eV had a threshold energy of 2.5 eV. In our model, the threshold energy represents the defect level where double negative to negative defect level,V$_{C}$C$_{Si}^{--/-}$, is 0.75 eV below the conduction band edge while negative to neutral, V$_{C}$C$_{Si}^{-/0 }$, is 2.5 eV above the valence band edge.