Type conductivity conversion in As-, Sb-doped p-CdxHg1−xTe under ion beam milling

The mechanism of p-to-n type conductivity conversion under ion beam milling (IBM) in extrinsically (As or Sb)-doped p-CdxHg1−xTe with x≈0.2 both experimentally and theoretically was studied. It has been experimentally revealed that the character of changes in the As- or Sb-doped samples after IBM is similar to those in the vacancy-doped p-CdxHg1−xTe and is determined by super-fast mercury interstitial atoms diffusion. The basis of theoretical analyze is the model of super-fast Hg interstitial atoms diffusion that has permitted to explain the similar conversion occurred in Hg vacancy-doped p-type CdxHg1−xTe. In this case the conversion involves only the simple intrinsic point defects. In an acceptor doped material a donor is generated due to the formation of a complex—interstitial Hg atom—As or Sb atom located in the Te site. This model provides reasonably good fits with the experimental results obtained for As- and Sb-doped CdxHg1−xTe epitaxial layers where the electron concentration in the converted n-layer corresponds to the concentration of the p-type dopants. Different efficiency of the conductivity conversion observed for As- and Sb-doped samples may be explained by different enthalpy of complex formation calculated for (AsTe–HgI) and (SbTe–HgI) pairs.