Duration: 1.12.2024- 31.12.2026

Project title: Radiation damage in Si and SiC based sensors / RADASS

Project code: IFA-CERN 07/2024

Project objectives:

The project proposed here is embedded as part of the research efforts in DRD3 working groups WG3 – Radiation damage characterization and sensor operation at extreme fluences, WG4: Simulation and WG6 – Wide Band Gap (WBG) and innovative sensor materials. which covers the Roadmap DRDT 3.3 on extreme fluence operation and reaches into all four Roadmap DRDTs for solid-state detectors wherever radiation damage is of concern. The final goal of the project is to achieve a fundamental scientific understanding of radiation damage processes in Si and SiC detector materials at low, high, and extreme radiation levels, as a necessary prerequisite for successful detector development. The work in the project address both, experimental and theoretical aspects, covering the full range from low to high and extreme fluences beyond 2x10¹⁶ n_eq/cm².

The main objectives of the project are:

O1) Characterize the radiation damage at the microscopic level in SiC and build up data sets on defect formation induced at low, high and extreme irradiation fluences.

O2) Establish the role of B, C, O and P in the formation of electrically active defects in Si PiN diodes exposed to irradiation fluences above 10¹⁵ n_eg/cm².

O3) Model the defects formation, dynamics and metastabilities in Si and SiC irradiated materials in connection with doping and extrinsic impurities;

O4) Device modeling and parametrization of radiation effects in Si and SiC over a large fluence range.

The electrical and structural characterizations will be performed on different defect engineered samples, by employing a large spectrum of experimental methods, suitable for defect investigations in samples exposed to different levels of irradiation, from DLTS - for low levels, to TSC/TSCap - for medium/high irradiations and further to EPR and FTIR techniques - for extreme high irradiation fluences (above 10¹⁷ n_eq/cm²). The parameters determined from experiments will be used as reference values or inputs for modeling both, the defect generation and kinetics, and the device properties. For theoretical modeling a multi-scale approach is employed aiming to understand the fundamental processes which occur in irradiated Si and SiC materials and devices, which combines tools designed to study the passage and impact of particles through matter (Geant4, TRIM), molecular dynamics (MD) using classical force-fields implemented in LAMMPS, first principle calculations (SIESTA), device simulation (COMSOL,TCAD) and Machine Learning techniques for by-passing numerically intensive simulations in the context of annealing schedules. The meta-stable defect states shall be identified and the corresponding transition states will be determined using nudged elastic band (NEB) calculations and further investigated by DFT calculations.

Stages/Activities (Year)

I. Calibration of the experimental setups, initiation of modeling procedures, preliminary investigations (2024)

I.1 DLTS investigation of uniradiated devices

I.2 Development of the FTIR experimental setup

II. Experimental and modeling of as irradiated sensors (2025)

II.1 Electrical and structural characterization

II.1.1. CV/IV/Resistivity and Hall effect measurements

II.1.2. DLTS/TSC/TSCap investigations

II.1.3. FTIR studies

II.2 Modelling and Simulations

II.2.1. GEANT4 and LAMMPS simulations

II.2.2. Computing models for analyzing the TSC/TSCap and FTIR data

II.2.3. Ab initio simulations (SIESTA)

III. Integrating the experimental and modeling results (2026)

III.1 Electrical and structural characterization of irradiated sensors following annealing treatments

III.1.1. DLTS/TSC/TSCap investigations of iradiated and annealed devices

III.1.2. CV/IV/resistivity and Hall investigations of iradiated and annealed devices

III.2 Modeling and Simulations

III.2.1. Computing models for analyzing the TSC/TSCap and FTIR data

III.2.2. GEANT4 and LAMMPS simulations

III.2.3. Ab initio simulations (SIESTA)

III.2.4. Parametrization of radiation damage