Spectroscopic ellipsometry studies of nanocrystalline silicon in thin-film silicon dioxide

Nanocrystalline silicon (n-Si) is formed in a silicon dioxide thin-film matrix by ion implantation followed by thermal annealing in forming gas at 1100°C for 1 hour. The ion implantation is performed using multiple implants with different implantation energies and doses to create a quasi-flat concentration of silicon atoms throughout the silicon dioxide film. These samples are then analyzed using spectroscopic ellipsometry to characterize their linear optical properties. Implantations with small doses (5 × 10²⁰ Si atoms/cm³) increase the refractive index by a small amount (Δn∼0.006 at 600nm), while implantations with moderate dose (5 × 10²¹ Si atoms/cm³) have a larger increase in refractive index and exhibit optical absorption above ∼1.9 eV (650 nm).