A method is disclosed for implanting and activating antimony as a dopant in a semiconductor substrate. A method is also disclosed for implanting and activating antimony to form a source/drain extension region in the formation of a transistor, in such a manner as to achieve high activation and avoid deactivation via subsequent exposure to high temperatures. This technique facilitates the formation of very thin source/drain regions that exhibit reduced sheet resistance while also suppressing short channel effects. Enhancements to these techniques are also suggested for more precise implantation of antimony to create a shallower source/drain extension, and to ensure formation of the source/drain extension region to underlap the gate. Also disclosed are transistors and other semiconductor components that include doped regions comprising activated antimony, such as those formed according to the disclosed methods.