The photosensitive optical absorption bands in Zn-treated and neutron-irradiated ZnSe single crystals

Zinc selenide crystals are irradiated by fast neutrons at room temperature and/or fired in zinc or selenium vapor. Optical absorption spectra of these crystals are measured from 450 to 2000 nm at 83 K. It is found that neutron irradiation and Zn treatment produce photosensitive absorption bands with peaks at 2.2 and 1.9 eV, which are enhanced by blue light irradiation and reduced by red light irradiation. The photosensitive 1.9 eV absorption band produced by neutron irradiation or Zn treatment has the same half-width, 0.36 eV. This band increases with the heating time of Zn treatment and then saturated at about 2 h and is removed by Se treatment. This band is related to the intrinsic lattice defects, that is, the Se vacancies. (author)