Radiation Induced Point and Cluster-Related Defects with Strong Impact to Damage Properties of Silicon Detectors

TL;DR

This study investigates radiation-induced defects in silicon detectors, identifying point and cluster-related defects from various radiation sources, and linking microscopic defect formation to macroscopic damage effects, especially under high radiation doses.

Contribution

It provides a comparative analysis of defects caused by different irradiation types and elucidates their impact on silicon detector performance, highlighting the role of oxygen concentration and defect complexes.

Findings

Point defects depend on oxygen content in silicon.

Cluster-related defects cause reverse annealing effects.

Damage mechanisms vary with radiation type and dose.

Abstract

This work focuses on the investigation of radiation induced defects responsible for the degradation of silicon detectors. Comparative studies of the defects induced by irradiation with 60Co- rays, 6 and 15 MeV electrons, 23 GeV protons and 1 MeV equivalent reactor neutrons revealed the existence of point defects and cluster related centers having a strong impact on damage properties of Si diodes. The detailed relation between the microscopic reasons as based on defect analysis and their macroscopic consequences for detector performance are presented. In particular, it is shown that the changes in the Si device properties after exposure to high levels of 60Co- doses can be completely understood by the formation of two point defects, both depending strongly on the Oxygen concentration in the silicon bulk. Specific for hadron irradiation are the annealing effects which decrease resp. increase the originally observed damage effects as seen by the changes of the depletion voltage. A group of three cluster related defects, revealed as deep hole traps, proved to be responsible specifically for the reverse annealing. Their formation is not affected by the Oxygen content or Si growth procedure suggesting that they are complexes of multi-vacancies located inside extended disordered regions.