Characterization of Thin p-on-p Radiation Detectors with Active Edges

TL;DR

This study characterizes active edge p-on-p silicon pixel detectors, analyzing electric field and charge collection, and compares their performance with p-on-n sensors, revealing advantages and limitations in detector edge sensitivity and charge collection.

Contribution

It provides a detailed experimental and simulation-based comparison of p-on-p and p-on-n active edge silicon pixel detectors, highlighting their electric field distributions and charge collection behaviors.

Findings

Sensitive volume extends to physical edge above full depletion

Edge pixels function well with good spectroscopic performance

Charge collection is lower in p-on-p sensors below 80 V

Abstract

Active edge p-on-p silicon pixel detectors with thickness of 100 $\mu$m 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 $\mu$m 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.