Optical and photoelectrical properties of Hg1−xCdxTe/CdTe epitaxial films with graded band gap

The infrared transmission and photoconductivity spectra of HgCdTe epitaxial films with graded band gap were investigated both theoretically and experimentally. Theoretical calculations were performed in the framework of the WKB approximation. The composition profile has been obtained from a fitting procedure. In order to reduce the total number of fitting parameters as well as to improve accuracy of this procedure the differential of the transmission versus photon energy curves was used. The best fit was obtained for an exponential composition gradient.