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Effect of Zn on the cation vacancy–isoelectronic oxygen pair in Cd 1 − x Zn x </mml:…

2004; American Physical Society; Volume: 70; Issue: 24 Linguagem: Inglês

10.1103/physrevb.70.245213

1550-235X

Salah A. Awadalla, Kelvin G. Lynn, Su‐Huai Wei, Csaba Szeles,

Machine Learning in Materials Science

The cation vacancy-isoelectronic oxygen pair $({V}_{\mathrm{Cd}∕\mathrm{Zn}}\text{\ensuremath{-}}{\mathrm{O}}_{\mathrm{Te}})$ was investigated in ${\mathrm{Cd}}_{1\text{\ensuremath{-}}x}{\mathrm{Zn}}_{x}\mathrm{Te}$ crystals and compared to it is behavior in $\mathrm{CdTe}$ using thermoelectric effect spectroscopy (TEES) and first-principles total-energy calculations. We found that the thermal ionization energy $E={E}_{v}+(0.184\ifmmode\pm\else\textpm\fi{}0.011)\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and trapping cross section $\ensuremath{\sigma}=(7\ifmmode\pm\else\textpm\fi{}4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}17}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}$ of the $(\ensuremath{-}∕\ensuremath{-}2)$ transition for the ${V}_{\mathrm{Cd}}\text{\ensuremath{-}}{\mathrm{O}}_{\mathrm{Te}}$ pair are identical to those found in $\mathrm{CdTe}$. In addition the concentration of the pair is much smaller in ${\mathrm{Cd}}_{1\text{\ensuremath{-}}x}{\mathrm{Zn}}_{x}\mathrm{Te}$ than in $\mathrm{CdTe}$ crystal for samples with the same nominal oxygen concentration. Using first-principles total-energy calculations, we found that under equilibrium growth conditions the lowest achievable formation energy of ${\mathrm{O}}_{\mathrm{Te}}$ is about $0.5\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ higher in $\mathrm{CdZnTe}$ than in $\mathrm{CdTe}$. This indicates that the addition of $\mathrm{Zn}$ to $\mathrm{CdTe}$ reduces the equilibrium substitutional oxygen concentration that can bind with the cation vacancy to form ${V}_{\mathrm{Cd}∕\mathrm{Zn}}\text{\ensuremath{-}}{\mathrm{O}}_{\mathrm{Te}}$.