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B.Caylar , M.Pomorski , P- N.Volpe , P.Bergonzo Diamond Sensors Laboratory CEA-LIST, Gif-Sur-Yvette, France José Alvarez Laboratoire de génie électrique de Paris (LGEP), Gif-sur-Yvette, France Alexander Oh University of Manchester, School of Physics and Astronomy, Manchester, United Kingdom
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B.Caylar, M.Pomorski, P-N.Volpe, P.Bergonzo • Diamond Sensors Laboratory CEA-LIST, Gif-Sur-Yvette, France • José Alvarez • Laboratoire de génie électrique de Paris (LGEP), Gif-sur-Yvette, France • Alexander Oh • University of Manchester, School of Physics and Astronomy, Manchester, United Kingdom • Thorsten Wengler • CERN, Geneva, Switzerland Novel 3D micro-structuring of diamond for radiation detector applications: Enhanced performances evaluated under particles beam.
Context • Non-ionizingenergylossinducesbulkdefects Dose increase [1] before irradiation after 1.2 x 1014 20MeV n.cm-2 after 1.97 x 1014 20MeV n.cm-2 [1] Michal Pomorski – PhD debate, Frankfurt University 07/08/2008 • When dose increases : • Defectsnumberincrease • Carrier lifetime reduction • CCE decreases
Context Traversingparticle 2D Electrodes 3D Electrodes [2] J.Morse, C.J. Kenney, E.M. Westbrook et al. / Nuclear Instruments and Methods in Physics Research Section A, 524 (2004) 236. • Advantages2: • Higher electric fields for a given applied bias voltage • Shorter drift time • Lower probability of trapping
Context 500 400 300 200 100 0 • After a 1016 particles.cm-2 dose • CCE drops to 10% with a 400µm distance betweenelectrodes • Is still 75% with a 50µm distance betweenelectrodes Distance betweenelectrodes (µm) 1E13 1E14 1E15 1E16 Integral fluence (particles.cm-2) Applications : - HEP (start detectors, BLM, Trackers, etc.) - Neutrons detection - Hadron therapy (ion tagging) • Improve charge collection efficiency for pcCVD • Improve radiation hardness for scCVD and pcCVD
Outline • Burriedelectrodes • Laser setup • Fabrication • Structural characterization • Optical microscopy • 2D Raman mapping • SEM imaging • Electronical characterization • I(V) characteristics • Charge collection efficiency • Conclusion
Burriedelectrodes – Laser setup Diamondholder Diamond x20 UV Lense NitrogenUV laser λ = 337nm • τ = 3ns • Repetion rate : 30Hz • 160µJ/pulse Si Diode XYZ Motorised stage • Tunableparameters • Scan velocity 1-1000 µm/s • Laser power 0-160µJ/pulse • Repetition rate 1-30 Hz
Burriedelectrodes – Fabrication Translation Graphitization XYZ Motorised stage • Photoluminescence during laser processing
Burriedelectrodes – Laser setup Diamondholder Diamond x20 UV Lense NitrogenUV laser λ = 337nm • τ = 3ns • Repetion rate : 30Hz • 160µJ/pulse Si Diode XYZ Motorised stage • Tunableparameters • Scan velocity 1-1000 µm/s • Laser power 0-160µJ/pulse • Repetition rate 1-30 Hz
Structural characterization – Optical microscopy • Optical grade scCVD sample 10µm diameter 20-80 µm diameter 700µm depth 150 µm • Back surface (Where graphitization starts) • Front Surface (Where graphitization ends) • Tilted sample
Structural characterization – Optical microscopy Detector zone Test zone • Micro-structured scCVD Diamond (optical grade) with crossed polarizers • Bulk strain mapping
Structural characterization – 2D Raman mapping • 2D Raman depth mapping obtained by integrating diamond peak 1000 CCD cts 1000 CCD cts 0 CCD cts 0 CCD cts 10µm 10µm • No micro-channel • Micro-channelwith cracks
Structural characterization – SEM imaging H2Plasma • Channel’s back sideafter laser processing • Channel’s back sideafter H2 plasma Holes are filledwith graphite
Electricalcharacterization – Graphite channels I(V) A • ρ(average) = 5.7x10-1 Ω.cm • R(500µm) ~ 2kΩ Current (mA) Voltage (V) • Match with nanocrystalline graphite given in literature3 [3] T.Ohana, T.Nakamura, A.Goto et al. / Diamond and Related Materials, 12 (2003) 2011 • Graphite’s channel resitivity
Electrical characterization – Experimental setup Fast Charge Sensitive Amplifier M.Ciobanu, GSI, Germany Signal Al back contact FCSA pcCVD Diamond Scope Al front contact R α Collimator Vbias = ±500V Am-241 Source 5.486MeV
Electric characterization – Electric field simulation V/µm Al contact Graphite channel α 700µm 200µm α Low CCE expected High CCE expected • 3D geometry but pseudo–3D detector
Electrical characterization – Deviceleakagecurrent A • 3D • Planar • I < 40 pA : fine for a detector application • pcCVD sample
Electrical characterization – Alpha characterization α α Amplitude has been normalizedwith the signal of a scCVD « electronic grade » diamond • Holes drift (pcCVD sample)
Electric characterization – Alpha characterization α α CCE (%) • Electrons drift (pcCVD sample)
Electric characterization – Alpha characterization • 3D • Planar • Polarizationstudy – Holes drift (pcCVD sample)
Electric characterization – Alpha characterization • 3D • Planar • Polarizationstudy – Electrons drift (pcCVD sample)
Summary • Electronically active graphite buried micro electrodes were fabricated suitable for detector applications • 3D geometryenable to improvepcCVD performance • Higher signal • Lesspolarization Thanks for your attention !