Characterization of thin p-on-p radiation detectors with active edges

Abstract

Active edge p-on-p silicon pixel detectors with thickness of 100 µm were fabricated on 150 mm float zone silicon wafers at VTT. By combining measured results and TCAD simulations, a detailed study of electric field distributions and charge collection performances as a function of applied voltage in a p-on-p detector was carried out. A comparison with the results of a more conventional active edge p-on-n pixel sensor is presented. The results from 3D spatial mapping show that at pixel-to-edge distances less than 100 µm the sensitive volume is extended to the physical edge of the detector when the applied voltage is above full depletion. The results from a spectroscopic measurement demonstrate a good functionality of the edge pixels. The interpixel isolation above full depletion and the breakdown voltage were found to be equal to the p-on-n sensor while lower charge collection was observed in the p-on-p pixel sensor below 80 V. Simulations indicated this to be partly a result of a more favourable weighting field in the p-on-n sensor and partly of lower hole lifetimes in the p-bulk.

Simulation study of signal formation in position sensitive planar p-on-n silicon detectors after short range charge injection

“…Due to their versatility and ability to reproduce not only generic behavior but also absolute values of measured silicon sensor characteristics before and after radiation, the Technology Computer-Aided Design (TCAD) numerical simulations have been applied as the next investigation tool in further studies of the reverse polarity charge signals. The reliability and accuracy of the TCAD simulations of the silicon strip detectors have already been documented in several publications and Ph.D. theses, including [7,8,[15][16][17][18][19][20] and [21,22], respectively.…”