Photo-induced current transient spectroscopy of single crystal Tl₆I₄Se

The compound Tl₆I₄Se is a promising wide band gap semiconductor for hard radiation detection at room temperature. To further improve its detection efficiency, native defects have been investigated using photo-induced current transient spectroscopy (PICTS). We observe two shallow acceptor levels with mean activation energies of 76, 175 meV, and two shallow donor defects 62, and 96 meV, respectively. No deeper donor levels are observed. The levels are attributed to native point defects. Defect capture cross sections in the range 10⁻²¹ to 10⁻¹⁸ cm² were measured. The small capture cross sections are attributed to the effective screening of the defects due to a large static dielectric constant. (paper)