Spatial uniformity of electron charge transport in high resistivity CdTe

Electron charge transport in high resistivity CdTe was investigated in terms of drift mobility, charge collection efficiency, and mobility-lifetime product. CdTe devices were produced from material grown by the Travelling Heater Method. Infrared microscopy was used to assess the quality of CdTe wafers, which showed a concentration of bulk defects and tellurium precipitates around the edges of the wafers. Laser-induced time of flight was used to measure the electron drift velocity, which was linear with respect to electric field at field strengths up to 200 V/cm. The measured electron drift mobility was 1040±20 cm2/V s. Ion-beam induced charge (IBIC) imaging of the device cathode was carried out to produce high resolution maps of signal amplitude and electron drift time. Excellent spatial uniformity was observed in the sample, and a value of 6×10−3 cm2/V was measured for the electron mobility-lifetime product.