Study on the composition deviations in CZT crystal grown by MVB method

This paper focuses on the composition deviations in Cd_0.96Zn_0.04Te crystal grown by MVB method and its influences on the crystal properties. The composition distributions were measured by X-ray energy spectrometer. The results showed that the values of (Cd+Zn)/Te are greater than 1 in the initial part of CZT ingot and decreased along the axis, which proves that there are still composition deviations in CZT crystal. The ingot was grown from the Cd-rich melt in the first-to-freeze region and from the Te-rich melt in the last-to-freeze region. The photoluminescence spectra show that there exists higher Te vacancy in Cd-rich CZT wafers and higher Cd vacancy and related defects in Te-rich CZT wafers. IR transmittance measurements indicate that higher deviation from the stoichiometric composition corresponds with lower IR transmittance.