p-Bulk silicon microstrip sensors and irradiation

Anticipating the requirement for highly radiation-tolerant silicon microstrip sensors suitable for the SLHC application, we have fabricated n-in-p microstrip sensors in p-FZ and p-MCZ industrial wafers which we then irradiated with 70MeV protons. Studies were made of the leakage current, onset of microdischarge, body capacitance, charge collection efficiency, and n-strip isolation at the fluences of nil, 0.7 10, and 7 10 1-MeV neutrons equivalent (neq)/cm. The bias and edge structure achieved holding the bias voltages up to 1000V. The full depletion voltages were about 160, 250, and 600V in the p-FZ and 1190, 500, and 840V in the p-MCZ at nil, low, and high fluences, respectively. The radiation damage helped to reduce the density of electron accumulation layer. The strip isolation in the p-MCZ sensors was found to be much better than in the p-FZ sensors; even the no-isolation structure isolated the strips at nil fluence at bias voltage above 50V. The lower density of electron accumulation layer in the p-MCZ could be attributed to an order less interface trap density in the /1 0 0S surface than that of /1 1 1S, the negative potential in the inter-strip region by the bias voltage, and the possible effect of high oxygen content in the MCZ bulk. r 2007 Elsevier B.V. All rights reserved. PACS: 29.40.W; 81.40.W