Effect of deep native defects on ultrasound propagation in TlInS₂ layered crystal

We have investigated p-type semiconductor–ferroelectric TlInS₂ by means of Photo-Induced Current Transient Spectroscopy (PICTS) technique in the temperature range 77–350 K for the detection of native deep defect levels in TlInS₂. Five native deep defect levels were detected and their energy levels and capture cross sections were evaluated. Focusing on these data, the influence of these defects on the longitudinal and transverse ultrasound waves propagation as well as the effect of electric field on ultrasound waves were studied at different temperatures. The acoustic properties were investigated by the pulse-echo method. The direct contribution of thermally activated charged defects to the acoustic properties of TlInS₂ was demonstrated. The key role of charged native deep level defects in elastic properties of TlInS₂ was shown.