PHOTOCONDUCTIVITY OF Cd_0.7Mn_0.3Se

The photoconductivity spectra of semimagnetic semiconductor Cd_0.7Mn_0.3Se have been measured at 50-300 K and in the wavelength range of 5500A to 8000A. It is found that the energy gap of Cd_0.7Mn_0.3Se changes with the temperature linearly, and the temperature coefficient (dE_g/dT) is about -7×10-4 eV/K. A photoconductivity peak which is related to Mn²⁺ is also found. This peak is located around 1.85 eV, nearly unshifted with variation of the temperature. The possible transition mechanisms in Cd_1-xMn_xSe have been discussed in the light of group theory and crystal field theory, and the results are in good agreement with experiments.