In this study, magnesium (Mg) ion‐implanted GaN crystals were evaluated as a candidate reference materials (RMs) for quantitative secondary‐ion mass spectrometry (SIMS)‐based Mg depth profile. The surface roughness remained extremely low, with R a ≤ 0.18 nm and R rms ≤ 0.24 nm, which is favorable for stable sputtering and depth profiling. SIMS analysis performed under optimized 16 O 2 + primary‐ion bombardment and positive 24 Mg + secondary‐ion detection yielded a well‐defined Mg distribution with a projected range ( R p ) of 195 nm and a peak concentration ( C p ) of 1.03 × 10 19 atoms cm −3 . The implanted Mg concentration was calibrated by relative sensitivity factor (RSF) using an implantation dose and was also determined from the known nominal implantation dose and the integration of 24 Mg + / 69 Ga + intensity ratio from the measured SIMS depth profile of Mg ion‐implanted GaN. In this experiment, the experimentally calculated RSF of 2.75 × 10 22 atoms cm −3 was used to calculate the Mg concentration in the Mg ion‐implanted GaN with an estimated relative uncertainty of approximately 15%. Thus, the ion implantation condition was intentionally retained to preserve the traceability of implantation dose and to avoid the Mg redistribution during ion implantation.
Byeon et al. (Sun,) studied this question.