Spectroscopic ellipsometry studies on polycrystalline Cd0.9Zn0.1Te thin films

Abstract

The pseudodielectric-function spectra, epsilon(E) = epsilon(1)(E) + iepsilon(2)(E), of polycrystalline Cd0.9Zn0.1Te thin films in the 1.7-5.5 eV photon energy range were measured by spectroscopic ellipsometry. ne measured dielectric function spectra reveal distinct structures at energies of the E-1, E-1 + Delta(1) and E-2 critical points due to interband transitions. The vacuum evaporated Cd0.9Zn0.1Te thin films exhibited zinc-blende structure with predominant (111) orientation. The rms roughness of the film evaluated by an ex-situ atomic force microscopy is 3.7 nm. Dielectric related optical constants, determined from the spectroscopic ellipsometry data are presented and analyzed. The optical constants of the film were also determined by using optical transmittance measurements, and results were discussed.