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Positron lifetime spectroscopy of defect structures in Cd 1– x Zn x Te mixed crystals grown by vertical Bridgman–Stockbarger method
Author(s) -
Gorgol Marek,
Zaleski Radosław,
Kierys Agnieszka,
Kamiński Daniel,
Strzałkowski Karol,
Fedus Kamil
Publication year - 2021
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520621004728
Subject(s) - ternary operation , positron , materials science , spectroscopy , cadmium telluride photovoltaics , positron annihilation spectroscopy , analytical chemistry (journal) , trapping , crystallography , electron , chemistry , positron annihilation , nanotechnology , physics , nuclear physics , ecology , chromatography , quantum mechanics , computer science , biology , programming language
Positron annihilation lifetime spectroscopy was used to examine grown‐in defects in Cd 1– x Zn x Te mixed crystals as a function of Zn content ( x = 0, 0.07, 0.11, 0.49, 0.9, 0.95, 1) and measuring temperature. All samples were prepared using the high‐pressure modified vertical Bridgman–Stockbarger method. The crystal structure and material phase were characterized by X‐ray diffraction. The positron lifetime spectra reveal the presence of both open volumes and shallow traps regardless of the sample composition. In particular, both average and bulk lifetimes are found to be much higher in ternary alloys (CdZnTe) than those in binary systems (CdTe and ZnTe). This originates from distinct differences in average electron densities and the nature of open‐volume defects between binary and ternary samples. Competition in positron trapping with increasing Zn content is observed between defects characteristic for both structural systems. Moreover, a clear correlation is shown between defects and the lattice thermal conductivity of studied samples. The applicability of the positron trapping model to CdTe‐based materials is discussed.