Characteristics of doped indium in Cd_0.9Zn_0.1Te grown by the Bridgman method

The Cd_1-xZn_xTe crystal is one of the key materials for room temperature x-ray and gamma-ray detectors. By the vertical Bridgman method (VBM) several indium (In) doped Cd_0.9Zn_0.1Te (Cd_0.9Zn_0.1Te: In) ingots have been grown. The characteristics of In in these ingots have been studied. It is found that the segregation coefficient of In in Cd_0.9Zn_0.1Te is 1.3. In is enriched at the grain boundary but homogeneously distributed inside the grains in the as-grown crystals. IR transmission measurements reveal that Cd_0.9Zn_0.1Te: In is almost opaque to IR emission when the wave number is larger than 1000 cm^-1, then is 24% transparent when the wave number is decreased to lower than this value. This phenomenon indicates that some In atoms are interstitial impurities and act as neutral donors. These In atoms bring out a donor level of 0.12 eV below the bottom of conduction band for Cd_0.9Zn_0.1Te: In. Resistivity measurements reveal that the resistivity is highly increased after doping of In into Cd_0.9Zn_0.1Te, and then In concentration is positive to raise the resistivity of Cd_0.9Zn_0.1Te: In.