A Spectroscopic Ellipsometric Investigation Of New Critical Points Of Zn_(1-x)mn_xs Epilayers

摘要

Zn_(1-x)Mn_xS epilayers were grown on GaAs (100) substrates by hot-wall epitaxy. X-ray diffraction (XRD) patterns revealed that all the epilayers have a zincblende structure. The optical properties were investigated using spectroscopic ellipsometry at 300 K from 3.0 to 8.5 eV. The obtained data were analyzed for determining the critical points of pseudodielectric function spectra, <ε,(E)> = (ε_1(￡)) + i<ε_2(E)>. such as En, E_0 + Δ_0, and E_1, and three E_2 (Σ Δ, Γ) structures at a lower Mn composition range. These critical points were determined by analytical line-shapes fitted to numerically calculated derivatives of their pseudodielectric functions. The observation of new peaks, as well as the shifting and broadening of the critical points of Zn_(1-x)Mn_xS epilayers, were investigated as a function of Mn composition by ellipsometric measurements for the first time. The characteristics of the peaks changed with increasing Mn composition. In particular, four new peaks were observed between 4.0 and 8.0 eV for Zn_(1-x)Mn_xS epilayers, and their characteristics were investigated in this study.