Study on Cd vacancy in CdZnTe Crystal by Positron Annihilation Technology

Positron lifetime spectroscopy of defect structures in Cd1–x Zn x Te mixed crystals grown by vertical Bridgman–Stockbarger method

“…The measured bulk lifetimes in binary CdTe and ZnTe crystals are 279 (1) ps and 260 (1) ps, respectively. These results are in very good agreement with previous experimental and theoretical works showing that b of CdTe is in the range 276-292 ps (Geffroy et al, 1986;Geffroy, 1988;Gely et al, 1989;Gé ly Sykes et al, 1991;Corbel et al, 1993;Polity et al, 1994;Kauppinen et al, 1997;Krause-Rehberg et al, 1998;Tessaro & Mascher, 1999;Peng, 1999;Martyniuk & Mascher, 2001;Li et al, 2012;Liu et al, 2013;Elsharkawy et al, 2016;Š edivý et al, 2016;Dannefaer, 1982;Keeble et al, 2011;Puska et al, 1989;Plazaola et al, 1994a,b;Barbiellini et al, 1996), while b of ZnTe lies between 254 and 266 ps (Krause-Rehberg et al, 1998;Tessaro & Mascher, 1999;Peng, 1999;Plazaola et al, 1994a;Pareja & de la Cruz, 1993;Puff et al, 2002;Hamid et al, 2005). This indicates that the 1D-STM model is applicable for both binary samples at room temperature (T = 293 K).…”

“…where 1 and 2 are the individual lifetimes and I 1 and I 2 are the corresponding intensities. The two-term decomposition is a typical result for CdTe-based samples in the bulk form (Geffroy et al, 1986;Geffroy, 1988;Gely et al, 1989;Gé ly Sykes et al, 1991;Corbel et al, 1993;Polity et al, 1994;Kauppinen et al, 1997;Krause-Rehberg et al, 1998;Tessaro & Mascher, 1999;Peng, 1999;Martyniuk & Mascher, 2001;Li et al, 2012;Liu et al, 2013;Elsharkawy et al, 2016;Š edivý et al, 2016), though Krause-Rehberg et al (1998) reported the lifetime spectra composed of the very high number of annihilation events (more than 10 7 ) that revealed the presence of a third component in CdTe:Cl samples. The average positron lifetime avg was calculated from the decomposition of the lifetime spectra as:…”

“…Moreover the temperature dependence of positron lifetimes may reveal the presence of impurities at concentration levels inaccessible for other techniques. Therefore PALS has been used many times in the past for the study of the structure of point defects in CdTe/CdZnTe/ZnTe systems (Geffroy et al, 1986;Geffroy, 1988;Gely et al, 1989;Gé ly Sykes et al, 1991;Corbel et al, 1993;Polity et al, 1994;Kauppinen et al, 1997;Krause-Rehberg et al, 1998;Tessaro & Mascher, 1999;Peng, 1999;Martyniuk & Mascher, 2001;Li et al, 2012;Liu et al, 2013;Elsharkawy et al, 2016;Š edivý et al, 2016;Dannefaer, 1982;Keeble et al, 2011;Puska et al, 1989;Plazaola et al, 1994aPlazaola et al, , 1994bBarbiellini et al, 1996;Pareja & de la Cruz, 1993;Puff et al, 2002;Hamid et al, 2005); however, the measured lifetimes have almost never been correlated with actual physical properties of samples.…”

Characterization of point defects in CdTe by positron annihilation spectroscopy

“…19 The vacancy defect lifetime and the calculated bulk lifetime, s B , values obtained here are in agreement with earlier studies of CdTe and Cd 1Àx Zn x Te. 15,16,[20][21][22][23][24][25][26][27][28][29] Previous work has provided clear experimental evidence that s B lifetime of CdTe is in the range of 280-290 ps. 15,16,20,[23][24][25][26][27] These studies also report a vacancy-related defect lifetime in the range $315-395 ps, which unambiguously demonstrate that these samples contain open volume point defects.…”

“…15,16,20,[23][24][25][26][27] These studies also report a vacancy-related defect lifetime in the range $315-395 ps, which unambiguously demonstrate that these samples contain open volume point defects. 15,16,[20][21][22][23][24][25][26][27]29 Positron annihilation lifetime spectroscopy is of particular importance because of the ability to resolve several different positron states; however, if two lifetime components are to be resolved, the second must be sufficiently greater than the first or a single weighted average component will be obtained. This ability depends on spectrometer IRF, the number of counts, and the number of lifetime components in the spectrum and typically requires the second lifetime to be in the range Â1.3-1.5 greater than the first.…”