Celso Figueiredo 26/10/2015 Characterization and optimization of silicon sensors for intense radiation fields Traineeship project within the PH-DT-DD section Integrated within the SSD (Solid State Detectors) team Supervisor: Christian Gallrapp on behalf of Michael Moll Michael Moll is deputy of the PH-DT group and co- spokesperson of the RD50 collaboration
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Celso Figueiredo26/10/2015 Characterization and optimization of silicon sensors for intense radiation fields Traineeship project within the PH-DT-DD section.
Characterization and optimization of silicon sensors for intense radiation fields Project Description - Motivation 3 As the luminosity of the LHC keeps being upgraded, silicon detectors used for particle tracking need to become radiation harder The signal performance of the silicon detectors degrades with radiation damage, due to the generation of electrically active defects in the silicon bulk (Michael Moll, 04/2010, “Recent advances in the development of radiation tolerant silicon detectors for the super-LHC”)
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Celso Figueiredo 26/10/2015
Characterization and optimization of silicon sensors for intense radiation fields
Traineeship project within the PH-DT-DD sectionIntegrated within the SSD (Solid State Detectors) team
Supervisor: Christian Gallrapp on behalf of Michael MollMichael Moll is deputy of the PH-DT group and co-spokesperson of the RD50 collaboration
Characterization and optimization of silicon sensors for intense radiation fields
Project Description:
Motivation
Defect Characterization
Performed Tasks:
Initial theoretical training
Initial practical training:
CV/IV
TCT
TCAD Simulations
Main project:
Aim
Performed Simulations
I-DLTS setup
Outlook on future work
Acknowledgements
Outline
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Characterization and optimization of silicon sensors for intense radiation fields
Project Description - Motivation
3
As the luminosity of the LHC keeps being upgraded, silicon detectors used for particle tracking need to become radiation harder
The signal performance of the silicon detectors degrades with radiation damage, due to the generation of electrically active defects in the silicon bulk
(Michael Moll, 04/2010, “Recent advances in the development of radiation tolerant silicon detectors for the super-LHC”)
Characterization and optimization of silicon sensors for intense radiation fields
Strip sensors: max. cumulated fluence for LHC and LHC upgrade
Pixel sensors: max. cumulated fluence for LHC and LHC upgrade
The LHC upgrade will require more radiation tolerant tracking detector concepts!
Also, it will be useful to study and clarify the underlying solid state mechanisms related to radiation damage and tolerance, which are not yet well understood!
Characterization and optimization of silicon sensors for intense radiation fields
Project Description – Defect Characterization
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Leakage Current Generation
Most effective closer to the middle of the bandgap
Charge Trapping
Impacts Charge Collection Efficiency of electrons and holes
Create Space Charge
Impacts Doping Concentration and Depletion Voltage
According to Shockley-Read-Hall statistics, the impact of defects on detector properties can be calculated if the following parameters are known:
σe,h – capture cross sections for electrons and holesΔE – ionization energyNt – defect concentration
A large number of defects levels have already been characterized (CiOi, VV, VO, …)
Characterization and optimization of silicon sensors for intense radiation fields
Initial theoretical training:
- Solid State and particle physics
- Semiconductor detector technology
- Phenomena of performance degradation in semiconductor detectors in
high radiation environments
Performed Tasks – Theory
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n+ layer
p+ layer
p-doped bulk
Transversing Particle
+
-
++++
+
- -- -
-Electron Drift
Hole Drift
VRB > Vdep
Characterization and optimization of silicon sensors for intense radiation fields
Initial practical training:
- Operation of silicon sensor characterization setups in the laboratories:
- IV: leakage current vs. applied reverse bias voltage analysis
- CV: capacitance vs. applied reverse bias voltage analysis
- TCT: Laser pulse induced transient current technique
- CV, IV and TCT measurements were performed on n-bulk silicon pad
detectors
- Introduction to Technology Computer Aided Design (TCAD) of silicon
detector structures, using the Sentaurus Synopsys TCAD software suite
Performed Tasks – Practice
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Characterization and optimization of silicon sensors for intense radiation fields
CV/IV Setup
Performed Tasks – CV/IV Setup
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Capacitancevs.
Reverse Bias Voltage Analysis
Leakage Currentvs.
Reverse Bias Voltage Analysis
Characterization and optimization of silicon sensors for intense radiation fields
TCT Setup
Performed Tasks – TCT Setup
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Induced current vs. time analysisIllumination by picosecond laser pulse
Characterization and optimization of silicon sensors for intense radiation fields
Simulations with the Sentaurus Synopsys software suite
- Powerful tool for simulation of 2D/3D semiconductor structures and devices:
- using finite element methods
- solver of coupled differential equations for semiconductors:
- Poisson’s equation, continuity equations for electrons and holes
- includes a wide range of models to calculate solid state physics mechanisms: