Semiconductor structures and methods of fabrication are provided for, for instance, inhibiting diffusion of active dopant within a semiconductor material. A diffusion-suppressing dopant is implanted via, an implanting process under controlled temperature, into a semiconductor material of a semiconductor structure to define a diffusion-suppressed region within the semiconductor material. One or more active regions are established within the diffusion-suppressed region of the semiconductor structure by, for example, implanting an active dopant into the semiconductor material. The implanting of the diffusion-suppressing dopant facilitates inhibiting diffusion of the active dopant within the diffusion-suppressed region.