A design trade-off study for n-channel delta-dolped Si/SiGe heterojunction MOSFETs has been performed using a combination of numerical simulation and analysis. A few design guidelines resulted from our study. We have shown that the cap and channel layer must always be made as thin as possible to reduce the separation of the mobile charge centroid from the surface, in which case better short-channel immunity, better leakage and driving ability will result. A deep potential well does not improve driving ability by much and leads to high leakage, although the short-channel immunity is better. A thick setback layer results in better leakage and driving ability but leads to poor short-channel immunity. A high delta-doping dose provides excellent short-channel immunity but leakage is high and driving ability is low. We summarize our study by constructing viable design regions enclosed by surfaces corresponding to performance constraints.