A SIMS calibration exercise using multi‐element (Cr, Fe and Zn) implanted GaAs

Multi‐element ( 52 Cr, 56 Fe and 66 Zn) implanted GaAs samples have been prepared specially for SIMS calibration. Absolute chemical measurements gave retained ion doses which agreed to within 12% of the nominal implanted dose (2.0 × 10 14 atoms cm −2 ). Comparative SIMS depth profiles with five instruments gave Cr mode depth data which showed a variability of 5%. After data normalization to a common mode depth (168 nm) the shape of all profiles showed good agreement. SIMS anàlysis of similar samples containing lower dose implants (1.0 × 10 13 atoms cm −2 ) showed that ∼50% of the Cr was contained in the near surface region (0–0.03 μm). This surface peak was not observed in profiles of samples which had been singly implanted with Cr. It is proposed that the Cr surface peak results from radiation enhanced out‐diffusion initiated by the subsequent Fe implant. Whilst the high dose multi‐implant samples showed a similar Cr surface accumulation, its magnitude in relation to the ion implanted dose, was smaller. These samples therefore form reliable calibration specimens for the simultaneous determination of the secondary ion responses of Cr, Fe and Zn in GaAs.