A Novel Self-Biased Linear Silicon Drift Detector

A novel linear silicon drift detector (SDD) is proposed in which the proper potential profile is established by the voltage drop along a unique p+ cathode implanted across the surfaces. This p+ implant, arranged in a zigzag shape, acts at the same time as voltage divider and field cathode and allows us to increase the sensitive area, improving also the uniformity of the thermal distribution and thus minimizing the fluctuation of the electron mobility on the sensitive zone of the SDD. The perturbations of the drift field due to the asymmetry of the strips constituting the zigzag cathode have been evaluated by solving analytically Poisson's equation for a simplified model of the structure. Three-dimensional numerical simulations have been carried out to prove the negligible amount of the perturbation and the effectiveness of the proposed structure. Based on this principle, a prototype has been manufactured at Canberra Semiconductor Company. Dynamic measurements of the time-of-flight of an injected charge prove that the linearity of the prototype and the drift uniformity in the anode direction are very high.