In one embodiment, the invention comprises: defining a first volume in a layer of a semiconductor device; calculating a probability of finding at least one dopant atom in the first volume, based on a dopant distribution of the layer; in the case that the calculated probability is equal to or greater than a pre-determined threshold, defining at least one additional volume in the layer substantially equal to the first volume; and in the case that the calculated probability is less than the pre-determined threshold: aggregating the first volume with a second volume adjacent the first volume, the second volume being substantially equal to the first volume; and recalculating a probability of finding at least one dopant atom in the aggregated first and second volumes, based on the dopant distribution of the layer.