Ellipsometric Studies on Sputter-Damaged Layer in n-InP

Abstract

Using multiple incident angle ellipsometry, the complex refractive index and the thickness of the damaged layer formed by SiO₂ sputtering deposition were determined. An analysis of a least-squares fit of the experimental values Δ _i and \varPsi _i to the theoretical results is carried out in three steps, where Δ _i and \varPsi _i are the phase change and the azimuth, respectively, at an angle of incidence φ _i . It is found that a point several hundreds of angstroms from the surface is damaged even though the thickness of the deposited film is only some tens of angstroms. The change in the complex refractive index n _d–jk _d and the thickness t _d of the damaged layer does not depend on the deposition time, but these quantities increase with increasing sputtering power. Typical values for n _d–jk _d and t _d are 3.684–0.389j and 640 Å, respectively at a sputtering power of 300 W.