Deep electron levels in undoped polycrystalline CdTe annealed in liquid Cd

The method of deep-level transient spectroscopy (DLTS) is used to determine the set of deep electron levels in undoped n-CdTe polycrystals grown by chemical synthesis from vapor phase in highly nonequilibrium conditions and then subjected to annealing in liquid Cd. After annealing, the electron concentration is found to increase from ∼108 to 1015 cm−3. Electron traps with deep levels E1 = 0.84 ± 0.03 eV and E2 = 0.71 ± 0.02 eV with total concentration ∼1014 cm−3 are dominant in the DLTS spectrum. The role of grain boundaries and intrinsic point defects in formation of deep-level centers and their effect on the value of conductivity after annealing are discussed. A relation between the level E1 and complexes of intrinsic point defects and relation of the level E2 to the Cdi point defect are considered.