dopant

This term is used almost exclusively within the fields of materials science, chemistry, and semiconductor physics. It describes a specific additive used to alter the intrinsic properties of a substrate, such as increasing the conductivity of silicon. The term carries a neutral, technical connotation and is distinct from the colloquial use of "doping" in sports, which refers to the illegal use of performance-enhancing drugs.

In a technical context, the dopant is the substance being added, while the process itself is called doping. The term is typically used in a precise, scientific register to describe the intentional introduction of impurities to achieve a desired electronic or optical effect.