The Iron States in Cd1−xFexTe in the Fundamental Gap Energy Range

The reflectivity, absorption, photoconductivity, and cathodoluminescence spectra for Cd 1-x Fe x Te (0 ≤ x ≤ 0.05) at 300 and 77 K are investigated. The measurements are carried out in the fundamental gap energy range. From the analysis of the experimental results, the energy positions and properties of Fe states in the CdTe matrix in the fundamental gap region are presented and discussed. It is concluded that the increase of the width of the fundamental gap with the change of temperature from 300 to 77 K leads mainly to the rise of the energy distance between the donor-like iron state 5 E and the bottom of the conduction band, whereas the energy distance between the iron state 5 E and the top of the valence band remains unchanged. The increase of the fundamental gap value with the decrease of temperature changes the energy positions of the excitation iron state 3 T 1 with respect to the bottom of the conduction band. Energy positions of iron states in the fundamental gap energy region as well as the increase of the energy width and density of these states with the rise of the iron concentration in Cd 1-x Fe x Te are reflected in the results obtained with the use of different experimental methods.