A pnCCD detector system for high speed optical applications 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

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

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

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

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

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

Internal quantum efficiency

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)

150 mm Wafer of recent fabrication

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

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

Schematic layout of 51 mm CCD with double-side readout

51mm 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 mm pixel size 256×264 pixel plus 2×4 “light insensitive” columns readout transfer to both sides

Performance overview 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 % Readout time Normal mode: 15 μs/row, i.e. 500fps Fast mode: 6.5 μs/row, i.e. 1000fps Pixel rate 70 Mpixel/s , split on 8 readout nodes Readout noise Normal mode → < 500fps : 1.8 e¯ (rms) Fast mode → 1000fps : 2.3 e¯ (rms) 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

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

CAMEX Amplification- and Readout-Chip 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)

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 ms constructing frame MIP and cluster analysis latency ~ 1.2 msec Example for a SH detector:

30 in total, free-to-ground, PC controlable, incl. monitor Overview Camera Controller cPCI-Bus 19’’ crate double height 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 32 2 2 2 2 80 MB/s 300m Front-End-Boards (incl. clock-drivers) CAMEX pnCCD-Chip Linux PC

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

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

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

Low and uniform noise performance 66×264 pixel, ⅛ of 51mm 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-

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 .

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

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