IBIC Characterisation of a Diamond Detector with 3-Dimensional Inter-digitated Electrode Geometry

In this work a novel 3-dimensional geometry of electrodes for single crystal CVD diamond ionizing radiation detectors has been fabricated and characterized, with the purpose of increasing the charge collection efficiency (CCE) with respect to standard inter-digitated surface electrodes geometries. The proposed geometry, fabricated by means of reactive ion etching of diamond along patterned structures, was investigated by means of preliminary Finite Element Method (FEM) simulations. Simulations evidenced the enhancement of the CCE in the inter-electrode region of 3D geometries with respect to that obtained by standard superficial electrodes, as a consequence of a higher electric field between vertical electrode plates. In fact, the straight field lines due to the 3D patterning of the electrodes results in a shorter travel path for the generated electron-hole cloud and in a higher drift velocity with respect to standard surface electrodes, contributing to a more efficient charge collection mechanism. The experimental results show a significant increase in the 3D-detector performance if compared with the results obtained by standard surface metallic electrodes.