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KIT – Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft www.kit.edu CERN Institut für Experimentelle.

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Presentation on theme: "KIT – Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft www.kit.edu CERN Institut für Experimentelle."— Presentation transcript:

1 KIT – Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft CERN Institut für Experimentelle Kernphysik (IEKP), KIT New approach to simulate radiation damage to single- crystal diamonds with SILVACO TCAD Florian Kassel, Moritz Guthoff, Anne Dabrowski, Wim de Boer

2 Florian Kassel Introduction to SILVACO TCAD Simulation of a diamond sensor Benchmarking of the simulation Approach to simulate the polarization effect of the diamond Conclusion Outline 2 ADAMAS – 3 rd Collaboration Meeting, Trento

3 Florian Kassel Is used in CMS silicon strip community to simulate electrical properties of the sensors Individual sensor designs of arbitrary materials possible Simulation can be done in 2D, quasi-3D and 3D Possibility to include a large selection of physical laws Introduction to SILVACO TCAD 3 ADAMAS – 3 rd Collaboration Meeting, Trento SILVACO TCAD: Tool to simulate the electrical, optical and thermal behavior of semiconductor devices

4 Florian Kassel Advantages of SILVACO TCAD in understanding radiation damage Electrical field distribution is directly linked to the detector efficiency Understanding of electrical field distribution is crucial! Electrical field properties depend on:  Drift behavior of charge carriers  Properties of traps in diamond bulk  Creation of space charges  etc, … Real measurement of electrical field possible with Transient Current Technique (TCT) measurement! Introduction to SILVACO TCAD 4 ADAMAS – 3 rd Collaboration Meeting, Trento can be simulated with SILVACO TCAD Exact simulation of TCT pulse necessary !

5 Florian Kassel Result quality Computing power Simulation of an alpha particle hit (TCT) 5 ADAMAS – 3 rd Collaboration Meeting, Trento D Quasi -3D 3D  Real charge amount  Overestimated charge density  z extension set to fixed value  Real charge amount  Overestimated charge density  z extension set to fixed value  Charge amount and density meet real value  Has to be rotationally symmetric  Charge amount and density meet real value  Has to be rotationally symmetric  Charge amount and density meet real value  All design possible  Charge amount and density meet real value  All design possible

6 Florian Kassel Initial charge deposition simulated in SILVACO:  Based on FLUKA simulation (5.0 MeV)  Cut of charge distribution in radial length to increase simulation speed Simulation of an alpha particle hit (TCT) 6 ADAMAS – 3 rd Collaboration Meeting, Trento Cut Alpha 5.0 MeV in diamond y – depth (cm)

7 Florian Kassel Benchmarking: 2D - SIMULATION 7 ADAMAS – 3 rd Collaboration Meeting, Trento Comparing of simulation results with a TCT measurement of a real sCVD diamond.  Charge carriers density dependent on thickness of 2D slice  charge carrier influence on electric field no longer negligible  High particle density leads to electrical field free regions  Diffusion becomes dominant  Charge carriers density dependent on thickness of 2D slice  charge carrier influence on electric field no longer negligible  High particle density leads to electrical field free regions  Diffusion becomes dominant

8 Florian Kassel Benchmarking: Quasi-3D SIMULATION (200V) 8 ADAMAS – 3 rd Collaboration Meeting, Trento Quasi-3D like model designed Parameters:  Thickness: 530 µm  Radial length: 100µm No traps simulated Mobility parameters for e and h drift used from thesis of M.Pomorski Quasi-3D like model designed Parameters:  Thickness: 530 µm  Radial length: 100µm No traps simulated Mobility parameters for e and h drift used from thesis of M.Pomorski

9 Florian Kassel Hole drift through diamond bulk 9 ADAMAS – 3 rd Collaboration Meeting, Trento V 200V ADAMAS – 3 rd Collaboration Meeting, Trento µm 530µm 0.0 ns 0.05 ns 0.3 ns 3.0 ns 5.0 ns

10 Florian Kassel Benchmarking: Quasi-3D SIMULATION (400V) 10 ADAMAS – 3 rd Collaboration Meeting, Trento Optimization of alpha particle simulation necessary !

11 Florian Kassel Benchmarking: 3D - SIMULATION 11 ADAMAS – 3 rd Collaboration Meeting, Trento …still calculating

12 Florian Kassel 12 ADAMAS – 3 rd Collaboration Meeting, Trento Quasi-3D: Simulation of diamond polarization 1) M.Bruzzi et al., Deep levels and trapping mechanisms in chemical vapor deposited diamond, Journal of applied Physics 91, 9 (2002),

13 Florian Kassel Quasi-3D: Simulation of diamond polarization 13 ADAMAS – 3 rd Collaboration Meeting, Trento Different e/h-trap parameters lead to an asymmetrical ionization of the traps  Asymmetrical electrical field distribution Increased recombination in low field region.

14 Florian Kassel Quasi-3D: Resulting TCT pulse for electron and hole drift 14 ADAMAS – 3 rd Collaboration Meeting, Trento Example sCVD_2012:  2.5E14 24GeV p eq at CMS  Thickness: 410µm  Mean after 750s (3.7MBq)

15 Florian Kassel Irradiation study planned: Investigation of the radiation impact on the electrical properties of a un irradiated sCVD diamond Stepwise irradiation (~5e12 n eq /cm²) till 5e13 n eq /cm² Proton irradiation performed at KIT (~23 MeV) Systematic measurement of electrical field effects:  Transient current technique (TCT)  Charge collection efficiency (CCE) Comparison of results with SILVACO TCAD simulation Cross checking of simulation results 15 ADAMAS – 3 rd Collaboration Meeting, Trento

16 Florian Kassel Quasi-3D simulation are feasible to simulate electrical properties of a diamond detector. Simulation of an alpha particle in good agreement to real measurement First approach of simulating the polarization effect in diamond  Increased density of donor traps assumed  MIP particle background simulated  Change of electrical field distribution and hence a change of the shape of the TCT signal observed. Conclusion 16 ADAMAS – 3 rd Collaboration Meeting, Trento Outlook: Simulation of MIP particle in order to calculate the CCE Modifying of traps in order to get closer to real results Simulation of improved diamond designs:  Split pads (BCM1F), etc… Outlook: Simulation of MIP particle in order to calculate the CCE Modifying of traps in order to get closer to real results Simulation of improved diamond designs:  Split pads (BCM1F), etc…


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