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XUV DIAMOND DETECTORS

XUV DIAMOND DETECTORS. Antonio De Sio. Dep. of Astronomy and Space Science University of Firenze, Italy. XUVLab Diamond activities. Research design and development of diamond based photodetectors

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XUV DIAMOND DETECTORS

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  1. XUV DIAMOND DETECTORS Antonio De Sio Dep. of Astronomy and Space Science University of Firenze, Italy

  2. XUVLabDiamond activities • Research design and development of diamond based photodetectors • Study and Characterization of single crystal and polycrystalline diamond detectors in VUV spectral range • Study and characterization of polycrystalline and single crystal diamond detectors in the X-ray Antonio De Sio WUTA 2008

  3. Collaborations • University of Firenze, Italy • A. De Sio, E. Pace, A. Giannini • Laboratori Nazionali di Frascati, INFN, Italy • A. Marcelli, C. Castellano, D. Hampai • University of Roma “Tor Vergata” • M. Marinelli, G. Verona-Rinati • Diamond Synchrotron Light Source • G. Cinque, G. Cibin, N. Tartoni • Italian CNR - GILDA BEAMLINE – ESRF • F. D’Acapito, S. Mobilio • Fraunhofer Institute – Freiburg • C. Wild, E. Woerner Antonio De Sio WUTA 2008

  4. Ideal XUV detector Very low noise Radiation hardness REQUESTS High sensitivity Large area Visible blindness Chemical inertness Antonio De Sio WUTA 2008

  5. Why diamond Solar Blindness 225nm Cutoff Wavelength High XUV sensitivity Energy Gap 5.5 eV Few Thermal Carrier No Cooling Low Dark Currents (< pA) Very Low Noise Low Power Absorption Chemical inertness Strong Chemical Bond Radiation Hardness Mechanical Robust Low Capacitance Low dielectric constant Electric Properties Fast response time High electric charge mobility Antonio De Sio WUTA 2008 High Signal Gain

  6. Summary • Diamond detectors • Dark Current • Visible blindness • Sensitivity spectra • Linearity of the response with flux • Response time • Photoconductive Gain Antonio De Sio WUTA 2008

  7. DETECTORS Antonio De Sio WUTA 2008

  8. Transverse geometry Coplanargeometry hν hν Diamond detectors MSM structure Antonio De Sio WUTA 2008

  9. External quantum efficiency Antonio De Sio WUTA 2008

  10. Interdigitated electrodes Diamond layer Diamond Devices: Single pixel detectors Antonio De Sio WUTA 2008

  11. Diamond Devices: Single pixel detectors Electrodes Diamond layer Antonio De Sio WUTA 2008

  12. Pixel array detectors • Lift-off photolitographic technique • Al contacts (blocking) • 20 m interelectrode spacing • 70 m pitch Antonio De Sio WUTA 2008

  13. DARK CURRENT Antonio De Sio WUTA 2008

  14. Photodetectors dark current Antonio De Sio WUTA 2008

  15. VISIBLE BLINDNESS Antonio De Sio WUTA 2008

  16. 100 E. Pace et al., Diam. Rel. Mater. (2000) 10 1 0,1 E = 2.8 V/mm UV / VIS > 108 0,01 1E-3 1E-4 External quantum efficiency 1E-5 1E-6 1E-7 1E-8 200 400 600 800 1000 Wavelength (nm) Visible blindness Antonio De Sio WUTA 2008

  17. UV Pulsed mode measurements • Responsivity lower than our detection limit at >1300 nm • Substrate contribution at >225 nm (Nitrogen impurities in the Ib substrate) • Stable and highly reproducible detector response • Undesirable memory effects as well as pumping ARE NOT OBSERVED Antonio De Sio WUTA 2008

  18. SENSITIVITY SPECTRA Antonio De Sio WUTA 2008

  19. Sample: SCD 31 Sample: SCD 8 He-Ne He EUV detection capabilities • Emission spectrum of a DC discharge He and He-Ne lamp • HeII 25.6 nm and 30.4 nm HeI as well 58.4 nm emission lines clearly detected • Good detection capability of the device even in this extreme UV spectral region • High signal to noise ratio, in spite of the pA range of the output photocurrent Antonio De Sio WUTA 2008

  20. EUV electro-optical performance Antonio De Sio WUTA 2008

  21. DUV electro-optical performance Antonio De Sio WUTA 2008

  22. LINEARITY Antonio De Sio WUTA 2008

  23. UV Pulsed mode measurements • 215 nm illumination • Linearity test by systematically varying the optical diffuser to diamond detector distance • Detector response as a function of the calculated incident energy • Good linear behaviour Antonio De Sio WUTA 2008

  24. Linearity • Diamond sc-HPHT • Coplanar contacts • Gold Contacts Antonio De Sio WUTA 2008

  25. RESPONSE TIME Antonio De Sio WUTA 2008

  26. Time response and PPC Antonio De Sio WUTA 2008

  27. Time response and PPC Antonio De Sio WUTA 2008

  28. Time response and PPC Antonio De Sio WUTA 2008

  29. Time response and PPC @160 nm • sc-HPHT • 1 V/μm Antonio De Sio WUTA 2008

  30. PHOTOCONDUCTIVE GAIN Antonio De Sio WUTA 2008

  31. Photoconductive Gain • Diamond sc-CVD • Coplanar contacts • Gold contacts Antonio De Sio WUTA 2008

  32. Photoconductive Gain De Sio et al. Appl. Phys. Lett. 2005 Single pixel device • Material from LIMHP-CNRS • Device built and tested in Firenze • Single crystal CVD diamond • Free standing • Mechanically polished • Au electric contacts on both surfaces Antonio De Sio WUTA 2008

  33. DUV electro-optical performance Antonio De Sio WUTA 2008

  34. Pixel array: cross talk • Pixel array characterization with 5 ns laser pulses at 215 nm (preliminary) • Three adjacent pixels of the array • Focusing of the laser beam on the pixel marked with * • Good spatial resolution (negligible cross-talk) and fast response times • Good sample homogeneity • Very good stability and reproducibility Antonio De Sio WUTA 2008

  35. Conclusion • Single crystal and polycrystalline diamond based UV single pixel and pixels array devices can be fabricated • Low dark current values • High XUV sensitivity was observed • Good response times • No persistent photoconductivity • No pumping effects • Negligible cross-talk in pixel arrays Antonio De Sio WUTA 2008

  36. Antonio De Sio WUTA 2008

  37. X-Ray Antonio De Sio WUTA 2008

  38. X-Ray detection • X-ray detection • Cu X-ray source 30kV • Fast response time (less than 0.2 s) • Good reproducibility • No persistent photocurrent • No memory effects • No Pumping effect • Good stability Antonio De Sio WUTA 2008

  39. Response stability 50 mins of simultaneous measurements with IC and diamond detector at 10 KeV. Differences are below 0.4% during the whole measurement. Antonio De Sio WUTA 2008

  40. Linearity with X ray intensity HPHT - SRS Loosen correlation between IC and diamond response Poly N doped - Stanford Antonio De Sio WUTA 2008

  41. Linearity with X ray intensity Antonio De Sio WUTA 2008

  42. K edge Fe Absorption HPHT 1b Diamond Polycrystalline Diamond N doped Antonio De Sio WUTA 2008

  43. EXAFS Signal Polycrystalline Diamond N doped HPHT 1b Diamond Antonio De Sio WUTA 2008

  44. Fourier Analysis Vs Theoretical Polycrystalline Diamond N doped HPHT 1b Diamond Antonio De Sio WUTA 2008

  45. EXAFS Results HPHT - 1b Poly N doped Good agreement between IC and Diamond detector and with the theoretical data Antonio De Sio WUTA 2008

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