Optical characterization of lattice damage and recovery in ion-implanted and pulsed excimer laser irradiated 4H-SiC

Infrared reflection measurements at near normal incidence between 400-7800 cm(-1) have been performed on ion-implanted and excimer laser irradiated bulk 4H-SiC wafers. A simulated annealing algorithm was used to fit a Lorenz-Drude model to the Reststrahlen region. The parameters of this model are directly related to the structure and electronic properties of the material. By examining the real and imaginary parts of the refractive index we are able to observe both damage induced by ion-bombardment and lattice recovery induced by excimer laser irradiation. The optimum laser fluence for lattice recovery is close to 1 J cm(-2), after which the laser appears to damage the SiC surface. Ultraviolet/visible reflectivity and photoluminescence provide additional evidence of an optimal annealing fluence. A consequence of the modeling is the deduction of estimates for the plasma frequency and carrier densities in annealed material.