Si atoms were recoil-implanted into GaAs by bombarding neutral (As+) or dopant (Si+) ions through a thin Si cap. The bombarded samples were subsequently rapid thermally or furnace annealed at 815–1000°C in Ar or arsine ambient. The presence of the recoiled Si in GaAs and resulting ni-doping was confirmed by secondary ion mass spectrometry and Hall measurements. It was found that sheet resistances of < 150 Ω/ can be achieved by this method. Capless furnace annealing in arsine ambient generally yielded better electrical results (especially for shallow implants, i.e., < 100 nm deep) compared to those obtained by RTA in an inert ambient with a Si cap. In the latter case, electrical activation deteriorated above 900°C due to high As loss and the deterioration was pronounced for shallow implants. Significant Si redistribution occurred during arsine annealing whenever the Si concentration (from recoil or direct implant) in GaAs exceeded 1×1019cm3 and the annealing temperature was > 850°C. Our present electrical data show that the recoil implant method is a viable alternative to direct shallow implant for n+ doping of GaAs.