S. Mitsui

Characteristics of the irradiated Hamamatsu p-bulk silicon microstrip sensors

Microstrip silicon sensors with p-bulk and n-readout are investigated as a radiation hard device for the Super LHC experiment. We evaluated the radiation hardness of the sensors fabricated by Hamamatsu Photonics through irradiation with 70-MeV protons up to the fluence of 5 × 1015 1-MeV neq/cm2 and with 60Co γs at a rate foreseen at the Super LHC. The strip isolation and punch-through properties are characterized in detail. Various strip isolation structures, p-stop, p-spray and both combined, are examined. The results are compared among commercially available MCZ and two types of FZ wafers.

TCAD simulations of silicon strip and pixel sensor optimization

Technology computer-aided design (TCAD), used in the semiconductor industry, simulates the semiconductor manufacturing process and the resulting device performance. We have used a device simulator to develop a highly radiation-tolerant n-in-p silicon strip and pixel sensors, both of which can operate at a very high voltage of up to 1000 V. We analyzed the electric field in the pstop structures, novel punch-through-protection (PTP) structures, breakdown in the edge region, etc. and compared the analysis results with the measurement results of test structures; our findings contributed to the development of guiding principles for optimizing the critical structures. The TCAD device simulator is a valuable and effective tool as long as relevant semiconductor physics models and their parameters are implemented. We have yet to understand the modeling of the surface-bulk interplay after proton irradiation, the leakage current generation in the dicing edge, and other phenomena.

Interstrip characteristics of n-on-p FZ silicon detectors

We report on the measurement of interstrip parameters of p-type silicon strip sensors which we are developing in a large collaboration to be used in a future tracker for the LHC upgrade. We measure on test structures with about 1 cm long strips the interstrip resistance, interstrip capacitance (at 1 MHz) and punch-through protection both pre-rad and after irradiation with 70 MeV protons to a fluence of 1.5×10^13 p/cm^2, corresponding to about 1 MRad, from prototyping runs with Hamamatsu Photonics and Micron Semiconductors. We report the values for a variety of isolation scenarios of p-stops, p-spray and a combination of both.