Study of mechanism of plasma surface modifications in Si by spectroscopic ellipsometry

Spectroscopic ellipsometry has been applied to study of plasma surface modifications in single-crystalline Si exposed to Ar plasma at room temperature. The complex dielectric functions of ion-bombarded layers were obtained from a new method for estimating the plasma-damage depth. Damage dependences of interband energy gaps and broadening parameters for the E1 optical transition were derived from the third-derivative spectra of dielectric functions. These parameters strongly suggest that Si surface exposed to Ar plasma has suffered from lattice expansion due to inclusions of Ar+ ions before lattice relaxation probably due to dislocation generation.