EFFICIENT DOPING OF GaAs BY Se+ ION IMPLANTATION

Efficient doping of GaAs by ion implantation has been obtained using Se+ ions. For a Se+ dose of 3 × 1012/cm2 implanted at 400 keV, a peak carrier concentration of 2 × 1017/cm3 occurred at a depth of 750 Å, with a standard deviation of 500 Å. Integration of the excess carrier concentration caused by the implantation indicates that for this ion dose at least 50% of the implanted ions are electrically active. For larger doses the doping efficiency decreases, and the carrier concentration approaches a limiting value of approximately 1019/cm3. The lowest observed sheet resistance for the implanted layer, about 250 Ω/square, occurred for a Se+ dose of 2 × 1014/cm2.