Results from 3-D silicon sensors with wall electrodes: Near-cell-edge sensitivity measurements as a preview of active-edge sensors

Silicon sensors with a three-dimensional (3-D) architecture, in which the n and p electrodes penetrate through the entire substrate, have been successfully fabricated. The electrode spacing can be less than the substrate thickness, allowing short collection paths, low depletion voltages, and large current signals from rapid charge collection. This paper gives results when the cylindrical electrodes of the earlier papers are replaced by a combination of cylindrical and wall electrodes-ones in which a trench, rather than a hole, is filled with doped polycrystalline silicon. The detection efficiency remains high to within a few micrometers of these wall electrodes, and is an indication that similar high efficiencies should be achievable near the physical edges of the proposed active-edge sensors.