Substitutional disorder effects on optical spectra of extremely heavily doped Si : P obtained by ion implantation and laser annealing

The optical reflectivity spectrum (2500–5000 Å) of extremely heavily phosphorus (P)-doped Si has been studied. The E₁ and E₂ peaks, which represent the completeness of the Si crystal, are slightly affected when doping concentrations are less than 10²¹ cm^-3 (2% Si : P). However,they appreciably degrade as the doping concentration increases from 10²¹ to 5×10²¹cm^-3 (10% Si : P). As the result of band calculations using a supercell configuration and pseudopotential method, we have been able to ascribe this behavior to the substitutional disorder effect.