The fabrication process of a two-dimensional position sensitive radiation detector (2-D PSD) with a 4 cm 2 active area is presented. Critical steps in the fabrication are emphasised. Edge effects represent critical problems in producing large area ion implanted silicon radiation detectors with low leakage currents and a high breakdown voltage (BV). Two methods have been used to increase the breakdown voltage of the junction: the use of i) floating field limiting rings (FFLR) and ii) field plates (FP). Several situations have been simulated analytically and numerically. A comparison of the theoretical results with the measurements realised using the detectors is presented. It is shown that a substantial improvement in the BV of the detector can be achieved by these methods.