Methodology for evaluation of mobility-lifetime product by spectroscopy measurements in CdZnTe spectrometers

A novel methodology is presented for extraction of the semiconductor electron and hole mobility-lifetime products by x- and γ-ray spectroscopy analysis. The methodology is based on the analysis of spectroscopy results, namely the maximal and the average charge collection efficiencies as discussed below, for different photon energies at various bias voltages. The methodology enables the evaluation of both electron and hole mobility-lifetime products without the need to use α particle measurements. The evaluation is carried out by a single parameter fitting of the models analyzed in this study. Mobility-lifetime products for CdZnTe substrates grown by Bridgman and high pressure Bridgman (HPB) methods are reported and compared. Typical values of ${\mu }_e{\mathrm{\cdot \tau }}_e{\text{=2⋅10}}^{\text{−3}}$ and ${\mu }_h{\mathrm{\cdot \tau }}_h{\text{=1⋅10}}^{\text{−5}}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V}$ are extracted for HPB grown CdZnTe with 10% Zn concentration. Values of ${\mu }_e{\mathrm{\cdot \tau }}_e{\text{=9⋅10}}^{\text{−4}}$ and ${\mu }_h{\mathrm{\cdot \tau }}_h{\text{=1⋅10}}^{\text{−7}}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V}$ are obtained for CdZnTe with 10% Zn concentration grown by the Bridgman method.