Surface passivation of CdZnTe wafer

CdZnTe wafer was passivated with NH₄F/H₂O₂ solution after the chemical polishing with Br₂-MeOH solution. The electricity property was characterized with I-V measurement and the surface composition was quantitatively measured with XPS analyses. I-V measurement showed that the CZT wafer surface was significantly passivated after the treatment. The dropping rate of current reduced with increasing the bias voltage. At the bias voltage of 10 V, the current dropping rate was the highest, about 73.7%. The critical field intensity was about 333 V/cm, at which I-V curves began to deviate from ohm law. Through XPS analyses, it was found that about 79.28% of Te in CZT surface layer was oxided to form TeO₂. The depth of oxided layer was about 3.15 nm. The composition of passivated surface became more close to the stoichiometric one.