The effect of the location of the high resistivity region within the crystal boule is investigated for 10% zinc with 1.5% excess Te. By varying the indium doping concentration in several CdZnTe boules, the region of high resistivity is changed along the vertical length of the crystal. The variation of the zinc concentration within the crystal boule is compared with the location of the high resistivity region along the length of the crystals. The concentration of zinc is extracted from FTIR measurements, and the segregation coefficient is calculated using data obtained from the CdZnTe crystals. The zinc distribution is plotted in terms of the location along the crystal length in order to correlate the concentration with detector performance. Radiation spectra obtained from these boules reveal a strong dependence between detector performance, and the relative location of the high resistivity region within the crystal. Initial results suggest that there are three semi-distinct regions along the length of the boule that give very different characteristics,
where it can be said that the best detector performance is in the middle region. It is determined that this middle region has a zinc concentration of ~9-11%, which varies slightly from the original concentration of 10%. The differences in the performance characteristics is discussed, and defect distribution within the crystal as the main source of the variation is suggested. Also, based on the results, it is believed that the role of indium is essentially to compensate the vacancies in the crystal, and therefore, secondary to the crystalline properties and impurities within the boule.