Formation of extremely shallow pn junctions with very low electrical resistance is a major stumbling block to the continued down scaling of microelectronic devices. Recent work in our laboratory has shown that the behavior of defects within silicon (and therefore dopants) can be changed significantly by controlling the chemical state of the surface. Certain chemical treatments of the surface induce it to act as an active "sink" for point defects that removes diffusing Si interstitials selectively over impurity interstitials, leading to less dopant diffusion and better electrical activation. The present work demonstrates such effects experimentally for dopants such as boron and arsenic in both crystalline and Ge pre-amorphized silicon wafers. Surface-based defect engineering was studied by annealing implanted Si according to various protocols with varying degrees of surface activity toward point defects. After implantation, specimens were heated to stimulate diffusive spreading of the implanted profile, with SIMS employed after annealing to monitor the spreading. SIMS measurements showed that the active surface caused less diffusion for boron and arsenic in crystalline silicon (c-Si). However, the boron dose loss in the case of the active surface was significantly higher than for the native oxide surface. This caused higher sheet resistance for the clean surface. Yet the percentage of activated boron was also higher for the clean surface. Thus, the atomically clean surface reduced transient enhanced diffusion and improved the percentage of dopant activation despite higher sheet resistance. Similar trends were observed in Ge preamorphized silicon. Additionally, the active surface dramatically reduced the number of end-of-range defects observed by electron microscopy.