Extending the dynamic range of fully depleted pnCCDs

pnCCDs are a special type of charge coupled devices (CCD) which were originally developed for applications in X-ray astronomy. At X-ray Free Electron Lasers (XFEL) pnCCDs are used as imaging X-ray spectrometers due to their outstanding characteristics like high readout speed, high and homogeneous quantum efficiency, low readout noise, radiation hardness and high pixel charge handling capacity. They can be used both as single-photon counting detectors for X-ray spectroscopy and as integrating detectors for X-ray imaging with count rates up to 10 4 photons of 1 keV per pixel and frame. However, extremely high photon intensities can result in pixel saturation and charge spilling into neighboring pixels. Because of this charge blooming effect, spatial information is reduced. Based on our research concerning the internal potential distribution we can enhance the pixel full well capacity even more and improve the quality of the image. This paper describes the influence of the operation voltages and space charge distribution of the pnCCD on the electric potential profile by using 2D numerical device simulations. Experimental results with signal injection from an optical laser confirm the simulation models.