Apparatus and method for use of solid dopant phosphorus and arsenic sources and higher order phosphorus or arsenic implant source material are described. In various implementations, solid phosphorus-comprising or arsenic-comprising materials are provided in the ion source chamber for generation of dimer or tetramer implant species. In other implementations, the ion implantation is augmented by use of a reactor for decomposing gaseous phosphorus-comprising or arsenic-comprising materials to form gas phase dimers and tetramers for ion implantation.