Effects of crystal growth methods on deep-level defects and electrical properties of cdznte:in crystals

Deep-level defects in CdZnTe:In (CZT) crystals grown by the modified vertical Bridgman (MVB) method and the traveling heater method (THM) were comparatively studied by thermally stimulated current (TSC) measurements. The trap density of Cd vacancy-related acceptor defects is found to be lower in THM-grown crystals compared with crystals grown by the MVB method, since the relatively low growth temperature of the THM will greatly reduce the loss of Cd and decrease the generation of Cd vacancies. Tellurium antisite-related deep donors are dominant in MVB-grown CZT, and Te interstitial-related deep acceptors are dominant in THM-grown CZT crystals grown by the Te-rich solution technique. The compensation of donor and acceptor defects leads to a low concentration of net free electrons in n-type MVB-grown CZT and a relatively high concentration of net free holes in p-type THM-grown CZT. The Fermi level in MVB-grown CZT is positioned below the conduction band by the antisite-related deep donor, while that in THM-grown CZT is positioned above the valence band by the interstitial-related deep acceptor.