Optical investigations of the CdTeSe and CdMeTeSe (Me=Mn, Fe) semiconductors

Reflectivity measurements have been performed for ternary semiconducting compounds CdTe1-xSex (x=0.1, 0.15, 0.20) and quaternary compounds Cd1-yMnxTe1-xSex (x=0.1, 0.2; y=0.05, 0.1) and Cd1-kFekTe1-xSex (k=0.02,x=0.006, 0.1, 0.2) in the 0.5-5.9 eV energy range at room temperature. In the reflectivity spectra, in this energy range, three distinct maxima were observed which according to Cardona's notation are known as E-1,E-1 + Delta, and E-2. For all samples it was observed that increasing the Se content results in a decrease in the intensity of reflectivity spectra and in the blurring of the spectrum structure. The spectral dependencies of optical parameters (reflection, absorption, refraction coeff.) have also been determined for quaternary Cd MeTeSe alloys (Me=Mn, Fe) by Variable Angle Spectroscopic Ellipsometry (VASE) and the surfaces of the samples have been scanned by Atomic Force Microscopy (AFM). Reflectivity data give comparable and even more reliable results than ellipsometry based on measurements of angles P and A. The influences of Mn and Fe on CdTe and CdSe base alloys are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.