The effects of incoherent light rapid thermal annealing and furnace annealing of arsenic‐implanted silicon (6×1015/cm2of arsenic at 70 keV) have been studied by x‐ray photoelectron spectroscopy (XPS) and secondary‐ion mass spectrometry (SIMS). The XPS analysis revealed two chemical states of arsenic with a 0.9‐eV chemical shift of the 3dcore level, which coexisted in both the as‐implanted and annealed samples. The arsenic with a higher binding energy is interpreted as substitutional arsenic, whereas the other arsenic component is assigned as either interstitial or clustered arsenic. SIMS and XPS results also indicate that surface segregation and clustering of the implanted arsenic during annealing are enhanced by the presence of implantation‐induced structural defects.