1. MOHAMAD KHALIL APC LABORATORY PARIS 17/06/2013 DSSD and SSD Simulation with Silvaco

2. Compton Telescope Concept Detector Design Simulations Outlook

3. Compton Telescope Concept

4. Last decade: X-ray domain High and very high Ɣ -ray domains instruments: INTEGRAL, XMM-Newton, SWIFT, Chandra, Fermi, HESS, MAGIC or VERITAS The 0,4-100 MeV range: Much less progress Difficulties in this energy range Minimal photon interaction probability Very high instrumental background induced by Cosmic rays Best sensitivity made by the COMPTEL instrument CGRO mission (1991 – 2000) COMPTEL instrument: two separate detectors Scatterer Calorimeter Classical Compton Telescope

5. Last decade: X-ray domain High and very high Ɣ -ray domains instruments: INTEGRAL, XMM-Newton, SWIFT, Chandra, Fermi, HESS, MAGIC or VERITAS The 0,4-100 MeV range: Much less progress Difficulties in this energy range Minimal photon interaction probability Very high instrumental background induced by Cosmic rays Best sensitivity made by the COMPTEL instrument CGRO mission (1991 – 2000) COMPTEL instrument: two separate detectors Scatterer Calorimeter Classical Compton Telescope

6. Compton Imaging Technique: Pioneered by the COMPTEL instrument Scatterer Calorimeter New Improvements : double-sided Si-strip tracking detectors (DSSD) No more need for a calorimeter (much lighter) fine spectral and position resolutions of modern Si detectors => better detection efficiency Silicon has a high capability of measuring polarization Large field of view of Silicon Source Simulation

7. Detector Design

8. Silicon micro-strip detectors are widely used for medical applications and in physics experiments as instruments to measure the position of a particle passing through the wafer bulk of the silicon detector Sadrozinski, H.F.-W., Nuclear Science, IEEE Transactions, 5752001, 933 - 940 Recent Progress

9. Silicon micro-strip detectors are widely used for medical applications and in physics experiments as instruments to measure the position of a particle passing through the wafer bulk of the silicon detector Sadrozinski, H.F.-W., Nuclear Science, IEEE Transactions, 5752001, 933 - 940 Recent Progress

10. A high resistivity n-type Silicon bulk A set of heavily n-doped strips placed on the top (n-side) A set of heavily p-doped strips on the bottom (p-side). The p-side and n-side are perpendicular to each other Double Sided Silicon Strip Detectors

11. DSSD as an ionizing chamber Localization in the XY-plane Energy deposition Double Sided Silicon Strip Detectors

12. DSSD as an ionizing chamber Localization in the XY-plane Energy deposition Double Sided Silicon Strip Detectors

13. What is a DSSD? DSSD as an ionizing chamber Localization in the XY-plane Energy deposition DSSD performance : Depletion voltage Electric Field shape Capacitance Leakage current Charge collection and charge sharing Double Sided Silicon Strip Detectors

14. What is a DSSD? DSSD as an ionizing chamber Localization in the XY-plane Energy deposition DSSD performance : Depletion voltage Electric Field shape Capacitance Leakage current Charge collection and charge sharing Double Sided Silicon Strip Detectors

15. DSSD Performance Simulation

16. SILVACO semiconductor simulation toolkit : Devedit:a tool capable of defining the structure to be simulated (2D and 3D) Atlas: device simulator that predicts the electrical behavior of semiconductor devices Deckbuild: a runtime environment for Atlas Tonyplot: a tool designed to visualize Tcad 1D, 2D and 3D structures and solutions http://www.silvaco.com/ C++ generation engines Input to SILVACO Runtime: few seconds to tens of minutes Simulation Tools

17. Objective of the simulation Depletion voltage Electric Field shape Capacitance Leakage current Charge collection and charge sharing Main simulation parameters: Thickness Pitch and strip width to pitch ratio Doping concentrations Simulation approach

18. Structure in 2D

20. Structure in 3D

21. Aluminum overhang

22. Depletion voltage

25. Depletion Voltage vs bulk concentration (or Resistivity)

26. Depletion voltage conclusions: Lowest bulk impurity concentration achievable 1,3 10 11 cm -3 (30 kohm.cm) Depletion Voltage vs bulk concentration (or Resistivity)

27. Depletion voltage

28. Depletion voltage conclusions: Lowest bulk concentration achievable Thicker detectors and/or lower ratios require more depletion voltage Depletion Voltage

29. Capacitance

34. Depletion voltage conclusions: Lowest bulk concentration achievable Thicker detectors and/or lower ratios require more depletion voltage Capacitance conclusions: Depends primarily on the ratio (favoring lower ratios) Depends secondarily on the thickness and the pitch (higher thicknesses and/or lower pitches) conclusions

35. Leakage current

37. Capacitance

38. Leakage current

39. Depletion voltage conclusions: Lowest bulk concentration achievable Thicker detectors and/or lower ratios require more depletion voltage Capacitance conclusions: Depends primarily on the ratio Depends secondarily on the thickness and the pitch Leakage current conclusions: Depends primarily on the thickness Depends on the applied voltage and the temperature Ratio has almost no effect conclusions

40. Charge Collection

41. Increasing the voltage Dead Zones

42. Increasing the thickness Dead Zones

43. Increasing ratio Dead Zones

44. Increasing ratio Dead Zones

45. Depletion voltage conclusions: Lowest bulk concentration achievable Thicker detectors and/or lower ratios require more depletion voltage Capacitance conclusions: Depends primarily on the ratio Depends secondarily on the thickness and the pitch Leakage current conclusions: Depends primarily on the thickness Depends on the applied voltage and the temperature Ratio has almost no effect Charge collection conclusions: Dead zones increase with the decrease of the ratio Beneficial to increase the thickness conclusions

46. Depletion voltage conclusions: Lowest bulk concentration achievable Thicker detectors and/or lower ratios require more depletion voltage Capacitance conclusions: Depends primarily on the ratio Depends secondarily on the thickness and the pitch Leakage current conclusions: Depends primarily on the thickness Depends on the applied voltage and the temperature Ratio has almost no effect Charge collection conclusions: Dead zones increase with the decrease of the ratio Beneficial to increase the thickness Signal formation

47. Depletion voltage conclusions: Lowest bulk concentration achievable Thicker detectors and/or lower ratios require more depletion voltage Capacitance conclusions: Depends primarily on the ratio Depends secondarily on the thickness and the pitch Leakage current conclusions: Depends primarily on the thickness Depends on the applied voltage and the temperature Ratio has almost no effect Charge collection conclusions: Dead zones increase with the decrease of the ratio Beneficial to increase the thickness Signal formation

48. Outlook

49. A GEANT4 program: Can deploy multiple silicon layers (DSSD) of adjustable thicknesses and adjustable separations Photon source of adjustable energy GEANT4 output: Energy and position of the gamma ray interaction event Used as input for SILVACO/C++ charge collection simulation: Imitate a single event Imitate multiple synchronized or delayed events Monter-carlo simulation ?- Problems with convergence for an extended simulation SILVACO Link with GEANT4

50. Probe Station

51. More tests on charge collection and dead zones Several available SSDs and DSSDs are available at APC and will soon be measured This will be vital to tune the simulation to have a better predictions for future DSSD demands (hidden parameters such has doping concentrations) A balloon flight Measuring the CRAB nebula polarization between 100 KeV and 300 KeV Foreseen in 2016-2017 outlook

52. Thank You