Performance of large-area silicon strip sensors for GLAST

We report on the performance of silicon strip sensors for GLAST, produced by Hamamatsu Photonics, Japan. The size of the sensors is 89.5 × 89.5 mm². They were processed on 6-in-high resistivity wafers. By now, more than 1000 of ultimately 11 500 sensors have been produced, and 622 have been investigated in detail. The average leakage current density is only 3.4 nA/cm² at 25°C. Such a low leakage current density enables us to screen out a sensor having few strips with high leakage current by looking at the total sensor leakage current instead of measuring individual strip currents. High breakdown voltage is also achieved. Of ten sensors investigated for high-voltage breakdown, all hold bias voltage up to 500 V without significant increase in the leakage current. The faulty strip rate is about 0.01% of 240 000 strips tested.