A pnCCD detector system for high speed optical applications

1. Semiconductor Detector Workshop 2005 Taormina/ June 19 – 24, 2005 A pnCCD detector system for high speed optical applications Robert Hartmann 1 , Hubert Gorke 2 , Norbert Meidinger 3 , Heike Soltau 1 and Lothar Strüder 3 PNSensor GmbH, Römerstraße 28, 80803 München, Germany Forschungszentrum Jülich, Leo-Brandt-Straße, 52428 Jülich, Germany Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85741 Garching, Germany

2. Overview • Principles of pnCCD • Optical properties • Detector format and geometry • Readout and data acquisition • Measurements and Performance • Summary and outlook

3. Principles of the pnCCD • Fully depleted 3-phase CCD • Back side illuminated • Cooled to -40º C .. -80º C (typ.) • Small detector capacitance ≈ 25 fF → low noise • One integrated FET per channel • Channel-Parallel-CCD → fast readout • p-implanted registers • High radiation hardness

4. Overview • Principles of pnCCD • Optical properties • Detector format and geometry • Readout and data acquisition • Measurements and Performance • Summary and outlook

5. pnCCD for optical applications • back illuminated detector • unstructured entrance window results in a homogeneous responsitivity • application of an ultra-thin rectifying implant leads to a high QE in the blue and UV region • easy to apply an anti-reflective coating • entire detector volume of 450µm is radiation sensitive • high quantum efficiency in the red and NIR region • fringing effects are negligible • small detector capacitance • high signal to noise ratio • highest electric field at readiation entrance side • narrow PSF • back illuminated detector • unstructured entrance window results in a homogeneous responsitivity • application of an ultra-thin rectifying implant leads to a high QE in the blue and UV region • easy to apply an anti-reflective coating • entire detector volume of 450µm is radiation sensitive • high quantum efficiency in the red and NIR region • fringing effects are negligible • small detector capacitance • high signal to noise ratio • highest electric field at readiation entrance side • narrow PSF

6. : Measured data : Model of Si-SiOx-SiO2 : Model of pure Si-SiO2 Interface Measured and modelled reflectivity of CCD entrance window

7. Internal quantum efficiency

8. Measurement of optical response at room temperature Optimized for CsI(Ti) scintillator readout (λ = 548nm) Standard entrance window, consisting of a thin SiO2 layer • Reflectivity of Silicon resp. Si/SiO2≈ 30% • Use layer stack of SiO2/Si3N4 as ARC • Technology allows to taylor responsitivity over a wide wavelength range Technological compatible ARC: • High QE in visible, maximum at 580nm • Optimum QE in NIR region • Blue and UV optimized (50% @ 300nm)

9. 150 mm Wafer of recent fabrication

10. Fringing effects due to multiple light reflection between detector front and back side

11. Overview • Principles of pnCCD • Optical properties • Detector format and geometry • Readout and data acquisition • Measurements and Performance • Summary and outlook

12. Schematic layout of 51 m CCD with double-side readout

13. 51m pnCCD with a double-sided readout,mounted onto a ceramic substrate • image area = 13.0×13.5 mm2 • chip area = 16.0×31.0 mm2 • 51 m pixel size • 256×264 pixel plus 2×4 “light insensitive” columns • readout transfer to both sides

14. Fast transfer time 25 μs/image (split to both detector sides) CTI ≈ 1 · 10-5 → total charge loss < 0.15 % Charge handling capacity > 105 e¯ / pixel Fill factor 100 % Normal mode: 15 μs/row, i.e. 500fps Fast mode: 6.5 μs/row, i.e. 1000fps Readout time Pixel rate 70 Mpixel/s , split on 8 readout nodes Normal mode → < 500fps : 1.8 e¯ (rms) Fast mode → 1000fps : 2.3 e¯ (rms) Readout noise Transfer binning (×2, ×3, ×4) 2000, 3000, 4000fps : 2.3 e¯ (rms) Operating temperature - 55º C for all measurements above Dynamic output range 70 dB Performance overview

15. Brief overview • Principles of pnCCD • Optical properties • Detector format and geometry • Readout and data acquisition • Measurements and Performance • Summary and outlook

16. Multi-correlated double-sampling filtering (MCDS) • Signal processing of all channels in parallel (132) • Serialized readout parallel to analogues signalprocessing • Selectable gains and operating modes • Electronic noise contribution less than 1 e- • Readout-speed per node up to 10MHz (i.e. 6.6µs per line on two readout nodes) CAMEX Amplification- and Readout-Chip

17. Data acquisition and real-time correction • 1000 frames / sec. • 264 lines / frame • 264 pixel / line • 70 Mpixel / sec. !!! • 140 MB/sec. Split on 4 DAQ boards • á 17.5 Mpixel / sec. • 2×14 bit flash-ADC Pipelined data processing in fast FPGA processor for real-time data correction and reduction Output of 1st CCD line is available with a latency time < 40 s • constructing frame • MIP and cluster analysis • latency ~ 1.2 msec Example for a SH detector:

18. Overview Camera Controller cPCI-Bus Power-Supplies 30 in total, free-to-ground, PC controlable, incl. monitor Fiber Interface ADC-Modul 1 ADC-Modul 2 ADC-Modul 3 ADC-Modul 4 Sequencer PS-Control Front-End-Boards (incl. clock-drivers) CAMEX pnCCD-Chip Linux PC 19’’ crate double height 32 2 2 2 2 80 MB/s 300m

19. Sequenzer 1 … 4 ADC-Boards á 2 ADCs Spare for Voltage Controller Optical Interface Data acquisition electronic system

20. Overview • Principles of pnCCD • Optical properties • Detector format and geometry • Readout and data acquisition • Measurements and Performance • Summary and outlook

21. Spectroscopic soft X-ray performance of pnCCD • Operating Temperature = -55° C • Overall noise contribution : 2.3 e- • All events reconstructed • FWHM for singles: 45eV

22. Low and uniform noise performance 66×264 pixel, ⅛ of 51m CCD (“worst” section) • 1 of 4 output nodes on one readout side • image plus storage area • operating temperature = -55°C • “1000fps” - timing scheme Mean noise = 2.3 electrons (rms) 98.8% of all pixel exhibit less than 2.7 e- noise 100% are below 3.1 e-

23. Increase readout speed for dedicated applications • Repetively readout of n lines with signal • merely transfer with no readout lines w/o signal • readout of next n lines • and so on … 40×40 SH with 5×5 Pixel: 1kHz → 1.3kHz frame rate . . . .

24. Conclusion • pnCCDs exhibit a high quantum efficiency from the optical to NIR region • device with 256×264 (13.0x13.5mm2) image size and a double side readout was successfully tested for a frame rate of 1000 fps • total readout noise of 2.3e- (RMS) was achieved in this mode at an operating temperature of -55ºC • binning in transfer direction allows 2kHz, 3kHz, ... frame rates with same noise figures due to very low leakage current • low and homogeneous noise performance over entire area (no bright or hot pixel, even at higher temperatures) • optical photon counting possible down to ≈ 8 γ/pixel

25. Back to the beginning Long term stability of pnCCD detector aboard XMM-Newton (1999): • Total area = 36cm2 • all 12 Sub-CCDs are still operating • same operating parameters (T = -90°C) • quantum efficiency unchanged • noise performance unchanged • slight radiation damage as expected: CTI ← 6 cm → FWHM after 5 years in orbit: Al-K (1.5 keV): 110 eV → 111 eV Mn-Kα (5.9 keV): 155 eV → 160 eV