Design of the AGIPD sensor for the European XFEL

For experiments at the European X-ray Free-Electron Laser (XFEL) the Adaptive Gain Integrating Pixel Detector (AGIPD) is under development. The particular requirements for the detector are a high dynamic range of 0, 1 to more than 104 12.4 keV photons per pixel for an XFEL pulse duration of < 100 fs , and a radiation tolerance of 1 GGy. The nominal operating voltage is 500 V, however for special applications an operation close to 1000 V should be possible. Experimental data on the dose dependence of the oxide-charge density at the Si–SiO2 interface and the surface-current density have been used in TCAD simulations and the layout of the pixels and guard-rings optimized. Finally the expected performance, in particular breakdown voltage, dark current and inter-pixel capacitance as function of X-ray dose are given.