Abstract: p- and n- layers in GaAs by dual implants with either Ge and Ga or Ge and As into GaAs have been produced. The amphoteric behavior of Ge implants is modified in a predictable manner through control of ion dose and annealing temperature by dual implantation. The (Ge+Ga) dual implants have produced p-type conductivity for all doses up to an anneal temperature of 900.degree. C. The (Ge+As) dual implants have yielded a significant enhancement of the n-type activity for ion doses .gtoreq.1.times.10.sup.15 /cm.sup.2, a conductivity type conversion for intermediate doses and little effect upon p-type activity for ion doses .ltoreq.3.times.10.sup.13 /cm.sup.2. By selecting appropriate ion energy, ion dose, and annealing temperature, formation of p-n junction is envisioned.