Processing and recombination lifetime characterization of silicon microstrip detectors

Three sets of silicon microstrip detectors have been processed and characterized. Recombination lifetimes of each set have been measured by Microwave Photoconductivity Decay (μPCD) method. In the this method, the silicon is illuminated by a laser pulse that generates electron hole pairs. The transient of the decaying carrier concentration is monitored by using a microwave signal. The recombination lifetime is a measure of the material quality i.e., defect/impurity concentration which affects the detectors’ electrical properties. A correlation between the recombination lifetime and the leakage current has been observed and discussed. The leakage current density in the best devices was about 6 nA cm−2 at 40 V. The average lifetime in the monitor wafer of this set was about 6500 μs. In comparison, average lifetime less than 1000 μs resulted in leakage currents of more than 100 nA cm−2.