Electrical compensation in CdTe and Cd0.9Zn0.1Te by intrinsic defects

The effects of two intrinsic deep levels on electrical compensation in semi -insulating CdTe and Cd-Zn-Te crystals are reported here. These levels were found in samples grown by conventional Bridgman and high-pressure Bridgman techniques. The levels were observed with thermoelectric effect spectrosco py at distinct temperatures corresponding to thermal ionization energies of E-d1=E-v+0.735+/-0.005 eV and E-d2=E-v+0.743+/-0.005 eV. The first level i s associated with the doubly ionized Cd vacancy acceptor and the second lev el was tentatively identified as the Te antisite (Te-Cd), which is thought to be complexed with a vacancy. The second level was found to electrically compensate CdTe and Cd-Zn-Te to produce high resistivity crystals, provided that the Cd vacancy concentration is sufficiently reduced during crystal g rowth or by post-growth thermal processing.