Doping, compensation, and photosensitivity of detector grade CdTe

We studied the resistivity, photosensitivity, photoluminescence, and surface photovoltage of CdTe crystals doped with Ge or Sn to extend our knowledge of the influence of the deep-donor level on compensation and afterglow effects. We demonstrated a strong correlation between photosensitivity caused by photoelectrons with Fermi-level variations near the Ge_Cd^0/2+ or Sn_Cd^0/2+ energy levels. Surface photovoltage measurements confirmed that when the concentration of residual acceptors varied along the direction of growth, then trapping conditions dramatically changed as a defect was converted from a neutral state to doubly charged positive one.