Semiconductor OneSource: Semiconductor Glossary -- Search For : arsenic, as

Term (Index)	Definition
arsenic, As	n-type dopant (donor) in silicon; features diffusion coefficient comparable to antimony and about order of magnitude lower that diffusion coefficient of phosphorous; donor of choice in very small geometry device manufacturing.
donor	element introduced to semiconductor to generate free electron (by "donating" electron to semiconductor); must have one more valance electron than semiconductor; common donors in Si: P, As, Sb and in GaAs: S, Se, Sn, Si, and C.
dopant	element introduced into semiconductor to establish either p- type (acceptors) or n- type (donors) conductivity; common dopants in silicon: p-type, boron, B; n-type phosphorous, P, arsenic, As ,antimony, Sb.
antimony, Sb	n-type dopant (donor) in silicon; used mainly to dope epitaxial layers; diffusion coefficient comparable to arsenic and about order of magnitude lower that diffusion coefficient of phosphorous.
arsine, AsH3	gaseous source of As for n-type doping of silicon by diffusion or ion implantation; highly toxic and flammable gas; must be handled with utmost care.
phosphorus, P	element from the 5th group of periodic table; common n-type dopant (donor) in silicon; about 10 times faster than As and Sb (other n-type dopants of Si) diffusant in Si.