Deep level characterization of undoped CdTe crystals

Abstract

Cadmium telluride crystals have been prepared using innovative techniques for the synthesis and purification of the feed charge. The growth of low impurity content CdTe crystals was performed by both physical vapour transport and Bridgman techniques. It was found that the resistivity of the obtained crystals was strongly connected with their stoichiometry. The characterization of the main deep levels in semiconducting and semi-insulating materials, carried out by capacitance and current techniques, is reported.

Photoluminescence and photoconductivity in CdTe crystals doped with Bi

“…[8][9][10] Similar conclusions have been drawn also for In and Cl dopants, which introduce shallow donor levels partially compensating the shallow acceptors present in the material. For example, in semi-insulating undoped CdTe grown in Te-rich conditions, a deep center has been found at 0.75 eV and attributed to a native defect; the most probable species is the Te antisite ͑Te Cd ͒.…”

Point defects and diffusion in cadmium telluride

“…This identification is also supported by Photo-EPR measurements [37]. However, other authors did not find this level also in Te-rich CdTe [75]. Finally, a deep level with energy close to the midgap was detected by different groups in n-type Al-doped and undoped crystals [76,77], in Cl-doped p-type and high resistivity crystals [49], in p-type low and high resistivity undoped crystals [74,78].…”

Boron oxide fully encapsulated CdZnTe crystals grown by the vertical Bridgman technique

“…Moreover, the boron does not appear to be electrically active in CdTe: in fact, samples grown with a boron oxide layer showed the same electrical behavior as samples grown by physical vapor transport without boron oxide, i.e. without a source of boron contamination [10,11]. The same conclusion was reached by Blackmore et al [12].…”