Charge sharing in double-sided 3D Medipix2 detectors

3D detectors are photodiode detectors with n- and p-type electrode columns passing through a silicon substrate. This structure gives a much smaller spacing between the electrodes than in a standard photodiode, greatly reducing the detector's operating voltage and collection time. The device structure also reduces charge sharing between adjacent pixels. This improves the image quality, making these detectors potentially useful for applications such as X-ray diffraction experiments in synchrotrons. A set of silicon detectors with a simplified “double-sided” 3D structure have been fabricated. After being bump-bonded to Medipix2 single-photon-counting readout chips, they have been tested using X-rays and alpha particles. The test results show that the 3D detectors have substantially lower charge sharing than a planar detector of the same thickness.