Effect of NaOCl-Polishing on Metal Organic Chemical Vapor Deposition grown GaAs Surface on Si Substrate by Spectroscopic Ellipsometry and Atomic Force Microscopy

Abstract

NaOCl-polishing of a metal organic chemical vapor deposition (MOCVD)-grown GaAs surface on a Si substrate has been studied by spectroscopic ellipsometry (SE) and atomic force microscopy (AFM). The AFM results indicate that the root-mean-square (rms) roughness of the surface of polished samples is typically 0.3 nm which is about 1/10 that of unpolished samples. The SE data also clearly indicate that the maximum ε2 (E2) value is ∼24.5 for polished samples. The thickness of rough surface and void fraction (an effective medium of rough layer consisting of bulk GaAs and void) for unpolished samples are obtained by using the effective medium approximation (EMA) and the obtained dielectric functions from the respective polished samples. The surface thicknesses obtained using this method compare well with those obtained by AFM measurements.