STUDIES OF DEFECTS IN N-TYPE CDTE BY CHARGE TRANSIENT SPECTROSCOPY

Charge transient measurements have been used to study deep levels in n-type CdTe single crystals. The samples, including In-doped, undoped, and Sn-doped single crystals, were grown by the Bridgman or the travelling heater method (THM). The temperature dependence of the capture cross section was investigated under the partial filling conditions. The activation energies of capture cross section were determined. For In-doped samples, the results indicate both levels Ec -0.66 eV (Bridgman samples) and Ec -0.68 eV (THM samples) are associated with the same indium-defect complex, but levels E c -0.34 eV (Bridgman) and Ec -0.32 eV (THM) exhibited different capture mechanisms. The unusual capture properties of the trap at Ec -0.61 eV in the undoped sample can be attributed to a doubly charged Cd interstitial. For Sn-doped samples, four levels were observed, and levels Ec -0.89 eV and Ec -0.43 eV can be related to the presence of tin.